Some nail polish removers actually have oils in them or things to "nourish the cuticles". Hypalon and PVC need different adhesives and different patch kits to work
. Make sure of what material you have, and use the right patch for it. 5200 is almost certainly NOT going to work, the patch kits often fuse into the plastic and 5200 won't do that.
If you have a small hole, there are also patch "plugs" that work by inserting a metal plate (which has a threaded rod coming up out of it) into the hole, then applying a top plate and clamping the two together. They're designed mainly for life rafts, where proper time and materials for patch kits aren't available.
The good news is, if you use the right patch materials, and the right solvent prep, the repair
WILL be just as good as new. You just can't take shortcuts on it though.