iPhone 7 stuck in boot loop after screen replacement

I have found that the proximity sensor is the issue most of the time, if you start the phone but disconnect the top cable to the camera it will boot just fine. Apparently the glass where the camera is looking through is causing some sort of false signal.

Make sure you connected the camera cable right. Ill plugged it the wrong way.

The main culprits for a boot loop on iPhone 7 after a screen replacement would normally be a damaged home button (or home button flex cable), (will eventually come on after 5-10 mins) or damaged front camera flex. If your really unlucky then it's possibly an ic as they are a known problem from dropping a iPhone 7.

Often times when replacing a component in an iPhone, the user may install the screws in the wrong place. Since they are of different length, it may cause a short somewhere inside of the device. Make sure no metal pieces are where they shouldn't be, and try again. You can also try to boot the device temporarily without any of the screws you unscrewed to see if that is the issue.

This is being called “Loop Disease”, and it is related to the Audio ic or the Baseband PMU. The solder joints beneath these IC’s are in a weak spot and will actually crack and/or separate from the board. Once this disconnects, the device cannot receive the data it needs upon boot up to actually boot fully. We have been repairing this issues like crazy at my shop here in the St. Louis area.