Chosen Solution
I just re-replaced the screen, changed the digitizer, and now the phone boots. Only problem left is the phone keeps trying to do data recovery and failing. I’ve tried flashing iOS 11.4 via 3uTools but it keeps giving a “recovery failed” or “do not disconnect device” error despite the cable being in pristine condition. I also have to manually put the phone into recovery mode because 3uTools fails to do so (something to be cautious about). I have also tried to update via iTunes which “worked” but the phone is still in a data recovery loop. What’s worst is that every flash or data recovery attempt makes the phone automatically disable itself without asking for the passcode for 1 minute or 5 minutes when finished. Please help me. This phone is eating at me. My old post where the question was solved and answered gives some history on the phone. It now boots and is constantly attempting data recovery. You can find the post here: iPhone 6s Plus dropped, cracked screen, now it won’t boot or vibrate..
Turns out the client gave the wrong passcode. Put the phone out of recovery mode via 3uTools and then used the new passcode they gave me. Phone restored itself and everything is fine. Had to fix vibration motor by taking it out, checking if spins, cleaning it, and putting it back in. Phone now works with no problems. Thanks.
Did you try restoring the phone if you do not need the data on it? It sounds like you did update only, it sounds like corrupt iOS firmware.
When you do an update in 3u Tools using retain data, this is the problem you face a lot. You will not have this problem with itunes. I have seen this a lot of times.
