Chosen Solution

Working on a friend’s iPhone after they left it on a charger for 2 weeks straight. Replaced the battery and it was on a boot loop, so I managed to get the phone into recovery mode (to me indicating that the lock button was working??) and do a restore. Everything worked and I’m in the process of getting it set up again, but now the lock button isn’t working. Could this be a software issue or maybe I didn’t reconnect a cable properly? Any help would greatly help!!

You just need to repair it you must of ripped it in the process.

What do you mean by the lock button? Do you mean the switch on the left side of the phone or the power button? If you mean the switch on the side of the phone then it’s very possible you damaged it accidentally while doing the battery replacement. Did the adhesive strips break on you? If so, you probably had to pry the battery out of the phone. When you do this, you want to pry from the left side and not the right as you can damaged cables on the left side of the phone.