It sounds like you may have damaged the ribbon cable for the screen. I'd suggest checking that all the traces are working: https://www.cemetech.net/forum/viewtopic.php?t=5161&postdays=0&postorder=asc&start=0 . Ribbon cable failure is pretty common so yours may have been about to break anyways, moving it around just accelerated the break.
Just so you know, you don't need the foil for the calculator to function, it's just emf shielding for FCC regulations.