Your problems seems to be both from the screen moving and the bootloader.
Uploading to the experimental bootlaoder v2 by Jonnection should solve the bootloader issues, ordering an USBAP is a good decision
About the screen moving around and having bad contact, you can clean the rubber contact on the back on the screen. The piece of plastic you're talking about is meant the hold the screen pressed against the PCB to prevent it from moving, picture
here.