Had to drill it out,once the cover was off it was little more than finger tight.Outta light will finish tomorrow.
I had the same issue you did. The impact screwdriver did the trick. Then make sure you clean the bolt holes out before you put the bolts back in.
Personal taste, but I prefer allen heads to torx, so when I take things apart, I replace them with allen bolts. You just have to make sure you replace them with the appropriate material and grade. The HD love of size 27 Torx is fine for initial assembly, but 27 isn't all that common in my experience.....