I am afraid if you soaked the whole unit in alcohol, the heat sink paste is probably ruined? If the unit seems to get hot or shut off spontaneously, I would consider taking it apart AGAIN, and cleaning and relating the heat sink with fresh new thermal paste. You can clean the old paste off with Alcohol, do you see why that worries me ;~)

I love how all of these say "back up the phone". That isn't helpful with a dead handset.

It's extremely rigid.

No, that's nonsense

The little flange that holds the wires and fastens onto the hinge screws should go on top of the hinge and not below? Just a thought.

Yes, this voids your warranty.

Double check the connection from the battery to the logic board and the logic board socket itself... Might have damaged by disconnect/reconnect.

That's a bad idea. using a metal tool to pry off glass is likely to end with an expensive broken front glass.

Suction cups are common. Find a couple and do it the safe way. I use some cheap ones that came with iPhone repair kit.