Chosen Solution

I was planning to reinstall Windows 8.1 on my laptop. I did by using a usb flash drive by using the legacy bios boot mode because it will not boot from it on uefi. It Installed perfectly but every time it started up it will be in legacy bios. 2 days after I tried to start it up by came up with the message os not found. I have tried f2,f8, f10 and f12 neither have worked. I cannot access recovery. I hope there is a solution to this as soon as possible because I need my computer back by next week

Guys, I was tinkering with the same Acer Aspire V5 laptop. After choosing legacy boot mode in the UEFI BIOS I was able to boot from linux USB drive, but after that I had no way to enter BIOS to change the boot mode back to SecureBoot. You tell the RTC battery needs to be removed to recall default UEFI settings, which is a whole pain in the ass - you need to disassemble the whole laptop. Instead, all you need to do is find 3 pairs of triangle-shaped contacts under the RAM cover. Motherboard WISTRON Petra UMA 11324-1 48.4VM02.011 These pairs of contacts are: G2101 - CLEAR CMOS G2201 - UEFI BIOS password clear G2701 - power button. So, to clear all the wrong settings you’ve done to the Acer V5 471 BIOS, you do not need to disassemble it, just short the G2101 for 20-30 seconds. Have fun! :-)

I FIXed IT!!!!!!!!!!!!!!!!!!!!! I encountered this problem today. Acer Aspire V5 will not display BIOS menu, no matter how many times you press F2, or whether you remove the HDD or whatever you try. The BIOS on that laptop can only be called from Windows 8 or 10 (not 8.1) , by restarting in recovery mode (aka safe mode) by holding the shift key when hitting restart on windows. So if the computer doesn’t boot into the HDD because of a miss-configuration of the BIOS, no luck for you. Today I was fixing a laptop with windows 10. I accessed the BIOS menu as described above (not F2) , then disabled safeboot and enabled legacy boot support and changed the order to be able to boot from CD, as I wanted to boot the computer with a live Linux DVD. The computer rebooted and I could use the DVD, no problem. Once I turned it off again and removed the DVD I got the fatal message error, OPERATING SYSTEM NOT FOUND. I played around and tried the usual tricks (windows installation media, fixboot, and all the usual command prompt things that you try in these cases). No luck. Then I realised I had disabled UEFI and Safeboot on the BIOS menu, well that’s the problem, that installation of Windows 10 will not boot at all in legacy mode. So I had to figure out a way of accessing the BIOS menu. I removed the HDD and got a blank one, I put it in the computer and left it ready to install a fresh new version of Windows 8 (not 8.1) on it, but for that I needed the installation media (which I didn’t have). While downloading an OEM DVD through a torrent client, I read this post. I thought, if I remove the motherboard battery and clear the BIOS storage it might go to default settings and enable again UEFI boot with Safeboot. And it did indeed!!! Getting to the bios battery is a pain on this poorly built laptop: remove battery, remove a myriad of screws, unplug cables, remove motherboard and get to the battery. I removed the battery for 2 minutes, in the meantime I plugged the power switch cable to the motherboard and pressed the button for 10 seconds. Put all back together and voilà!!! It works again. So now I can finally cancel the 4 gb download of the Windows 8 OEM DVD. Though I believe installing a windows 8 on a fresh HDD (you need a spare one, of course), booting that one, then restarting in safe mode (recovery mode) and going to UEFI menu should also let you change BIOS settings again.

I simply found the easiest way. Just download rufus 3.1 1320 Open it, load the iso that you want to installed select GPT in the menu and then create. Plug the flash drive and it will installed the new os.

When reinstalling your OS, you most likely deleted your recovery partition if that is what you were referring to with recovery. F12 should have given you a boot menu, and F2 should take you in to BIOS. Most of the times it’s just a timing issue when to press these buttons. Usually while boot logo is displayed. Press these buttons repeatedly after powering on until (in case) “operating system not found” is displayed. Also be sure that your keyboard is functional. If not, an external USB keyboard will help. Oh! And the “OS not found” might refer to some other thumb drive, external hard drive or SD card connected to the computer. Worst case you can take out your BIOS battery from your motherboard for 10 minutes and while no power source connected to it press the power button for about 10 seconds, than place the small 3V battery back again. Now powering on will give you an error report with an option to either enter bios or boot up. Hope this helped, keep me posted

NON of this helped. I did try all of it before getting here. I even reprogram the bios with my special machine and nothing. So far the only thing it helped was booting with a w8/8,1 Core x64 dvd installation. By default most w8 bios had cd/dvd booting first than the hdd. The root of the problem is that you had your bios reseted to default somehow. GL!! PD: use f9/f12 to boot the dvd and wait for it to boot up. a good tip to know if your w8 computer came originally with 8 or 8.1 is to boot up the core version of each one and the one that does not ask for a key is the one. Also if you computer is originally w8 you can go ahead and install w10 and it will activate after changing in the bios the w8 key for the w10 key with no problem. I do it everyday even a year after the free upgrade is gone.. DONT WORRY IT DOES NOT BOOT TO THE BIOS OR IT DOES NOT SHOW THE BOOT MENU, just do it and it will work.

I tried every single one of the solutions: shorting signal traces in the RAM bay Removing the CMOS battery Pressing F2, F10, F+myA$$ NONE of the mess worked for me. The ONLY thing that worked was restarting Windows while holding the SHIFT key then going into the Advanced options and choosing UEFI BIOS setup…. Then and ONLY then was I able to switch off the secure boot and boot to a USB stick and install the OS on a blank drive. This is a dismal design for a laptop. Acer should be ashamed of themselves for selling such garbage.

I have this problem also. My disk was already failing and i did replace my HDD, ending up with the “Operating System Not Found” error at the startup. No matter what f1-f12 you press you cant do anything. Tried everything, shorting the g2101, dismantling it just to remove that CMOS battery, even broke some of the screw locks at the joints, i even tried installing a windows 8 on my desktop to the new laptop HDD just to check if it will boot, but no luck. I almost smash this laptop, haha. yet I solved this by downloading Windows Media Creation Tool from microsoft. just run it, select an OS, select a USB drive or Disk, its pretty easy and it will install the newest version from microsoft and make you a bootable windows installer. I selected windows 10, then it will download, just let it finish, then i put it in my acer v5 571 then press the power on, and Voila! it booted! then i proceeded with the formatting. from what i read is it makes an UEFI bootable disk. So in short, i didnt end up opening the bios, just get a UEFI bootable USB or disk and that will do it.

Hello and good afternoon to all, just wanted to let you all now that unfortunately I had all of the above troubles with my Acer V5-751. non of all the solutions did work I was for 4 days disassembling and reassembling it to try all the solutions that have been stated on this chat. thanks any way to all off you. the way I did solve my problem ( the fact that I get the message " operating system not found" and no way to enter the bios or to boot from cd-rom/DVD / USB new blank HDD or with OS on it did not work. so I was left with a laptop not booting any more !! the chance wanted that my brother in law had a ASUS x551 with windows 8-1 originaly installed from manufacture. the think is that both of them to replace the HDD need to be disassembled completely so I said what the heyk one more time !! so I put the hdd of the Asus in the Acer and what do you know it started !! w8 tuck 3-4 minutes to configure the new hardware ! and boot correctly so I made the change to do the boot in bios. I restarded in bios change it to legasy and replace the hdd Asus with a new SSD with w10 installed on it ( wich by the way did not want to boot in the previous situation, THIS TIME did boot !! thanks to all ! Ciao

Solved!

  1. You will need a windows 8 8.1 or 10 Disk must be UEFI disk
  2. Insert windows disk into DVD drive it should boot automatically if not then press F12 then acer logo appears.
  3. Your computer now should boot into windows recovery chose to Boot into UEFI menu.
  4. Now when you in UEFI menu you will be able to make any necessary BIOS changes then save and reboot your computer.
  5. Now all should be working and windows Legacy mode supported.

Windows 8 restart click while holding Shift key enabled me to tell my Acer Aspire V5-571 to boot from USB HDD in while I had my bootable Fedora 27 Server iso installed.

for notebooks get any edition windows CD in it it will automatically start booting from CD drive.

FIXED! The QUICK WAY to resolve is to INSTALL windows 10 in UEFI in ANOTHER HARD DISK — after the installation the BIOS automatically reserve to factory setting.

hi guys boot computer in to windows. (If windows is already installed on your hard drive) if not please read note end of this post. 1:-Restart computer by holding SHITF key 2:-Wait 1or 2 min depend on your computer speed 3:-Menu pop up select Advance options 4:-Select UEFI setting 5:-another menu pop saying to change setting computer will restart here we go computer start go in to bios and you can change setting Also you will be able to see F2 function on the screen. Please Note if there is no OS installed on your laptop follow this procedure, If not install windows on test hard drive with UEFI compatible USB with another laptop with same chipset Intel or AMD. Thanks Mani

Follow these steps 1 check keyboard then try 2 reset bios then try to enter bios menu Remember external keyboard dis not work on operating system not found

I think your acer v5 backed to uefi boot mode,try flash your usb to uefi,message me when it work ;) PS:i tried

I have solved this problem…. Hold the ESC and F2 key.. For 5 secounds… After that u will enter into bios mode from Security U should change boot order to Legal…. After that Press F10… AndAnd Ur done… NOTE PLEASE COPY FULL HDD…. On Windows installation u have to Delete all Partions and make a new Partions….. Otherwise it will not install…. THANKs for Reading…

After trying for a long time, I was able to access Bios after updating it to the latest version on the Acer website. This allowed access with the F2 key during system startup. Another option that worked with me was the one mentioned by Miki on 5-02-2016.

i finally fix this problem by bios update . i accidentally change setting to legacy and this shift key solution dint work because os not found error . i make a bootable win 8 usb with bio/mbr support i extract VA410218.exe with 7zip and copy this extracted files in win8 bootable usb .now boot with usb and go to repair —> advance—>msdos—> and in command prompt type launch.bat and follow instructions :)