Stripped screw in key fob

Use a drop of super glue to hold the screwdriver in place? There shouldn't be that much torque on the screws.

You can drill it too, but you might damage it

 

I think that I would try a tiny screw extractor with an electric drill set to the "reverse" position. Hopefully that will not cause damage to the square plastic battery cover.

 

Ok, so technically it's the screw head rounded out rather than the thread stripped.

I find that when a small phillips head is messed up like that, a small flat blade screwdriver can often do a better job of gripping it than the correct phillips driver can. If you have a set of small flat blade jeweller screwdrivers then go through them and see if you can find one that is just the right width to get a grip on it. This technique has worked for me many a time.

 

Need to define the problem better.
The above suggestions are good ( except maybe for the superglue one) IF the problem is that the slots in the screw head are rounded out.

If, however, it is the actual screw threads that are stripped, thereby causing the screws to turn but not back out........
Then the solution often is to simply start prying the case halves apart to put pressure on the screws as you turn them.

 

Good tips! …however it might be the threads of the plastic housing which are stripped, in which case the holes may be fixed by inserting the end of a tooth-pick (or a splinter of wood) soaked in Elmers (or some other) wood-glue, and then re-use the original screws (cabinet maker's trick for fixing broken hinges) hope this helps - Wil

 

That is actually what I meant. The screw threads exist on both the male part and the female part.

 

Buy a replacement on eBay and exchange the internal bits.
OEM 2004 2009 Toyota Prius Key Fob Keyless Entry Remote Fccid MOZB31EG | eBay
You can also get a silicone covering for your fob that might hold it together.

Good Luck!