Chosen Solution
Since i got my MacBook it had this problem but i didn’t bother to fix it until now, it has a new replacement battery, new ram total 8GB, new 500gb kingston ssd and some other things It’s working perfectly now and it is running MacOS Catalina 10.15.7 ( the keyboad backlight had the same problem whit MacOS Sierra and High Sierra I will attach a few pics of the problem so you can see what i mean (and sorry if they are a bit blurry) And thanks in advance
Well this is not too bad! You’ll need to pull the logic board to gain access to the keyboard following this guide MacBook Pro 13" Unibody Late 2011 Upper Case Replacement. The backlight assembly which is what you see first will need to be removed and you’ll need to replace the LED’s that have blown (from a junker) or just replace the entire backlight assembly Book Pro 13" Keyboard Backlight Sheet or the full uppercase MacBook Pro 13" Unibody (Early 2011-Mid 2012) Upper Case.
