Chosen Solution
It all started with a screen replacement. Battery was fine and screen worked good after the 1st replacement then the screen stopped working so I ordered another when installing the replacement all went well except the battery says ‘service’ now and wouldn’t charge past 3% and kept going into a restart loop every 3 minutes, further throughout today before I packacged it up for amazon shipment the phone was really delayed in touch and was on 1% it turned off one last time and ever since it started doing the apple logo restart loop but literally every second. It wont even power on with or without being connected to a charging cable. The only way itll stay on is if I put it into Recovery mode itll stay on and display for the whole time. After that its the same restart loop. I used all the right screws, no drops or anything. Battery and screen are both 3rd party but I never had issues with the battery before this 2nd screen replacement. Any idea?
Have a look at this other question and @refectio ‘s anwer and pictures enclosed. I wouldn’t be surprised if you had exactly the same issue. What are the consequences of jumping a broken FL11 next to the battery
Try another battery which is fully charged. Also try some working screen with iphone. And test iPhone does it work or not. Then you will have exact idea where there is problem with battery or logic board.
Definitely try another battery and screen before assuming the logic board has a problem. The battery communicates with the iPhone. That’s why it has 3 pins. It “talks” with the phone to tell it how charged it is,the condition of it,etc. If you used a 3rd party battery,there’s a higher chance of this internal circuitry being defective. If you have an oem battery,or the original laying around,you should try it. You can just lay it on top of the other battery and plug it in. The fact it was working fine before,you used all the right screws,and only worked on the battery and screen means it really should be one of those 2 causing the issue. But of course there are other possibilities. Sometimes you can knock off a component right next to the battery connector and it can cause issues with battery data. Do you still have the original screen(if so,does it work enough to test)? You can also try another screen too,if you already tried another good battery. Oem parts are the most reliable to test with. A bad screen or battery can cause itunes errors and boot loops. I’ve also seen bad camera flex cables cause rebooting on my moms iPhone.
