Chosen Solution
I replaced the battery last week with an ifixit battery. and it was working fine until today when it shut down due to low battery. Now after charging it won’t start up. I get the Apple for a while then it goes into the spinning wheel thing for a while and then back to the Apple logo. It is stuck in this loop. Won’t power on..
It is possible that the battery is defective. You should measure the voltage of the battery directly on it’s connector. If you are getting less than 3.5V, then the phone will not boot. This could be due to a bad battery or a defective charge circuit on the logic board. I would also test the charge brick and Lightning cable with another device to be certain they are okay.
Try opening the phone and disconnecting and reconnecting the battery. Another issue with battery replacement is the Tristar charging chip has been known to go bad. This occurs when cables are not Apple certified. Also you may try another battery to rule out a bad battery.
