Phone won't power on after screen replacement

Hi!

So it went like this: I did the replacement, kept track of the screws, everything was fine.

I reassembled everything and turned the phone on and it was shiny and fine, but the home button felt stiff and too deep. So I went back in to screw it tighter.

For a minute I lost the clip for the fingerprint sensor, and (probably stupidly) tried to turn it back on (completely reassembled) without the clip.

By this point I had also tightened the screws holding the home button in place :S.

Tried to turn it on, just a black screen and no vibrations, but when I plug it into the laptop it gets recognised as if it's working fine- *except* that there is a message saying that there is a problem with the phone and it needs to be updated or restored (which I tried to do, but it turned out I don't have enough storage to update, and different error messages keep coming up when I try to restore, but I think that's a wifi thing...)

Then I found the clip, opened the phone again, put it back in, closed it up, and it was exactly the same situation. Black screen, no vibrations, recognised by laptop.

Is it possible that I damaged the logic board? Is it really that easy to do? Do the connectors from the screen (at the top) connect to the logic board? Because I didn't disconnect them again after I did the replacement the first time (after which the phone worked fine except for that home button issue). Is it possible to damage the logic board by screwing the home button in too tightly? If the problem was screwing in the home button too tightly, is there a part I can replace instead of replacing the whole phone?

I would be so grateful for any advice! Amateur Hour over here!

Thankyou,

Frankie