I agree. And when reassembling the wifi antenna, I connected the two plugs first, which worked fine, and only after that stuck the antenna back to its sticky place.

Where there is the 2,1mm philips srew holding the taptic engine (left), there is a tiny piece of metal under the srewhead. Note its orientation, take it out and dont't lose it taking out the taptic engine, then reinstall it when reassembling. When reassembling, the said fixing hole of the taptic engine is not on top, but has to be pushed under a little metal piece, it won't even fit on top. Then reinstall the tiny metal piece and put the screw in.

Same thing here. I am missing a contact in the replacement display, which is the terminal to a flatband cable buried in the displays plastic frame in the original. (Antenna ?) This contact connects to a pad on the back cover. But everything on my phone seems to be working fine, bluetooth, nfc, gps,wifi,cell. Any idea ? In the picture the contact is top/right close to the rim.

I had to move over from old to new assembly:

rubberpart next to speaker contacts

flat plasticpart under speaker

speaker

rubberpart between speaker and front camera, sits then on two tiny sensors on motherboard

all 3 cameras

Replacing cures power button and fingerprint sensor issues. I tried to cure a non functional power button with contact spray. This didn’t revive the button but killed the fingerprint sensor, too. Replacing the part cured both problems. Turn on assistive touch in settings to power down the phone (if you dont want to just rip out the battery).

Next time I will try the alcohol method.

I ran into a not workin front camera after a screen replacement on Iphone4. I found out that I had broken the tiny jumper on the main board when I pried off the headphone plug. That jumper is next to the right upper corner of the headphone/volume button plug (yellow marked in step 17 of relacement guide), you can see it in the picture as two silvery dots. If your prying tool sits on that jumper when levelling the plug off, it is history. I took a ampoule of conducting silver liquid, but instead of shaking it I took some of the sediment out with a thin wire and aplied a tiny blob over the two remaining soldering pads left. And alas, it worked ! Front camera is ok again. Thanks to those who found out about that jumper.