The screen fell off but is still operational, any tip on how to resemble it until a replacement screen is available?
Tried to put it back on but it just falls off again.
Is double-sided tape an option?
yeah, have been considering it, but bit concerned about leaving a lot of glue residue in the phone for after I replace the screen, but I am running out of options, so this might be the best I have.
I totally dropped my phone, you see one corner is chipped, so this is on me for sure.
As I mentioned before:
The screen is a design flaw (german).
I had a FP4 to repair (as an Angel) where the same happened, i used double sided tape (a really narrow one - 2mm) and it is still fully functional. So shouldn’t be a problem. 
The screen is originally also taped (you can try to remove the old tape - but be sure not to scratch anything).
It seems that this happens from time to time on some FP4’s. 
This has also just happened to me.
I see double sided tape suggested, but any reason not to use a few small dabs of super glue?
I wouldn’t want to reduce recyclability, but given it was glued anyway (albeit with tape) would it make any difference?