I just took out my radio tray to do my first bit of maintenance.
When I went to reinstall it, I'm not sure how the tray sits. The two screws that you loosen, how do those 2 plastic blocks lay?
Put the tray in with the screws loose.
The plastic "blocks" will slide down on the inside of the mounting rails.
When you snug the screws up, the blocks will "push out" and grab the mounting rail to hold the tray in place.