Hellllllllllllllllllllpp fixing hole in roof

Well that's much better than 4 feet square. :) The caulking around the vent should peel off with a bit of effort. If you still need to open up the roof after removing the caulk I would still cut down each side of the hole by about 2 inches per side and leaving the front side of the hole still attached. The thought is that the original roof is solid, so you want to make sure the patch overlaps the hole enough to give it some strength. Lay a piece of something under the rubber but on top of the roof to cover the hole. Then just tape it all back up. the tape will look different and hopefully keep you from stepping on that spot again. You could taper the patch, but truthfully the Eternabond tape will seal it well enough even over a 90 degree edge to prevent leaking.