[HTC U12+ Questions & Answers] VidJunky:
Just replaced mine

I just replaced mine yesterday and it was more difficult than any other one I've done in the past. Anyway I never found one single video on YouTube that showed the screen removal and pretty much had to play it by ear. There are a few videos that show the disassembly of the U12+ and each stops before removing the screen. My advice is to remove everything from the frame, I managed to piece together enough from the videos to know there are 15 screws to remove, one video said 14 but there's one more that's hidden until you've gotten under the motherboard holding the front facing cameras. Knowing I wanted to keep it simple I didn't remove all of the antenna wires, there's one at the bottom that's under the speaker cover that I left attached so I only disconnected it from the motherboard. Then the other I only disconnected near the vibrator, leaving it connected at the motherboard, so each piece had one wire that stayed connected. Meanwhile you'll have to undo every other plug on the device and with a little persuasion everything fell out. (Don't attempt to remove the button/pressure sensing strips along the sides!) Once you are down to the frame, and for me the ear piece speaker, I used a heat gun to soften the bond between the glass and the frame. It doesn't loosen up very easily, they are really bonded together. I got most of it and then began to chip away at the broken glass. You'll want a good heat gun for this part. I had to set mine to 300F to really get it to loosen up and then work mm by mm around the edge getting all of the glass and glue out of the track. This probably took me a half hour or more. I used E6000 glue but only because I would have had to order B7000 or any other recommended glue. E6000 is a good glue but just because many of the other videos I watched used B7000 I would have liked to use it too.

To install the new screen I used a syringe filled with my glue to follow the small glue track around the edge of the frame. Don't worry about squeeze out because this glue is very forgiving and wipes away easily with IPA Alcohol and a rag. I followed the old glue placement, adding a little extra near the bottom corners and a dab around the ear piece speaker holes. Then it's just reversing the process to assemble the electronics. Now here is another word of warning, the plugs are so small and some are not easy to align but be sure they snap into place and are flat when installed. I made the mistake of not getting the display plug flat and had to do a partial disassembly to correct the issue.

I didn't glue the back on but think I might today just to try and achieve the waterproof level the phone shipped with. You may have to glue yours but I had previously broken the back and already replaced it and the replacement came with a double sided adhesive strip that was still pretty sticky. If I remember correctly the original back was glued on and probably wouldn't have stuck if I had tried to just replace the back as I did.

One other note. After being disassembled and pulling the battery my finger print scanner didn't want to work. In fact it didn't even show up in the menu when I went looking for it but restarting the phone again caused it to show up. My advantage with the double sided adhesive was I was able to test everything and use the phone for a full day before committing to gluing the back on. Now that I know everything is working, the phone is charging and it all seems good I can glue the back on.

Best of luck