Maybe the OP is tool challenged like I am.
-PB Blaster should be used on the top and lower part of the faster = let it soak, the longer the better
-pound the head with a hammer to vibrate the threads
-careful use of a propane torch(an essential basic tool everyone should have) to heat the fastener, either the head or any exposed threads
>.>>>extreme caution should be used when near painted, plastic or fabric materials<<<<<
>>>a fire extinguisher has to be nearby or at least a water spray bottle and wet clean rags<<<<
-try grabbing the bolt head with vice grips, moving CW and CCW direction in very small amounts(try tapping bolt with hammer)
you work the threads loose with very small movements back and forth to create some looseness and then increase the amount
-you may need to heat again
Note_-you may be able to make the bolt head usable - bash with hammer to tighten the torx recess and tap the torx bit in to seat firmly
-try the back and forth movements but gently as not to kill the torx recess.
There are many ways to a solution - mine works for me.