Hello!
So, I've removed the old screen, and battery has been unplugged when removing and inserting the new one. The new lcd/digitizer however turns black after about 10-15 seconds, just about when it's supposed to load the password screen. Tested with the old one again, works fine.
I have not soldered on the old sensor as I wanted to test the replacement screen first and I don't want to void the warranty. Home flex has been transferred.