Battery connector damaged while replacing screen - view for more detai

@lilteslas, Unfortunately your photos aren't really of high enough resolution for us to make any definitive judgements based on them. From what little I can see, it doesn't look like the battery connector on the logic board is damaged; here's yours and a good one side by side.

Likewise, there may be a chance the upper pin on your battery is damaged, but again, I can't tell for sure from your picture.

The thing is, you've got more than one issue going on here. The battery contains a circuit called the Battery Management System, or BMS, that the processor talks to for temperature, health and cycle information. If it can't talk to the battery, you will get those battery health issues you've already seen, and may experience boot loops as well if it can't read the temperature sensor.

Replacing the battery may get rid of the boot loops, but Apple has started pairing BMS circuits to the phone so replacing the battery will mean a permanent loss of health information. If indeed the connector on the battery itself is damaged, your best solution would be to find a shop that is experienced with microsoldering and have them replace the connector. That will restore full functionality to your phone. Your only other choice is to pay Apple to replace the battery or use their self service program, which may save you some money, but you'll still have to buy the battery from them and rent their equipment to do the repair.

Anyway, despite the issues you're seeing with the battery, none of that is related to Face ID. There was a brief period where Apple had iOS set up such that replacing a screen resulted in the loss of Face ID, so I'm wondering if your phone has one of those versions. If that's the case, then the solution is as simple as updating iOS to a newer version.

It does seem odd that it worked before the problem with the battery happened though. Did you use a device programmer to transfer the True Tone data from the old screen to the new one? That could conceivably contribute to the brightness issue. You should also be expecting a warning message about the screen possibly not being genuine (even if it is) as Apple has also started pairing screens to the motherboard. You have to unsolder a chip from the old screen and replace it on the new one to avoid that issue. Again, Apple can fix that if you pay them to replace the screen or use the self repair program.