This problem arises because most torx kits do not come with a #27 bit in them and a #25 is used by mistake. They must be purchased seperately.

Easiest way to eliminate this problem is to use the #27 Torx bit to remove these fasteners, while many use a #25 by mistake, it fits sloppy and usually ends up striping the head of the bolt, but for now you can use a drill that is slightly larger by a size or two than the shaft of one of the bolts you have already removed and drill the head (s) off the stripped screws. Drill only the head off and when it pops off, then move on to the next one. Once you have taken the heads off the striped ones and removed the others, the cover comes right off, and then you can usually remove the ones that you drilled the heads off with your fingers from the back end of the bolt, unscrewing it out the front as usual. This method eliminates the possibility of doing damage to the cover itself. Real easy and it works most every time. Good luck.