After a myriad of problems including my old belt falling off, then my new serpentine belt falling off, my old battery dying, and then my new battery dying, and then losing power while my car was moving, I've decided to change the belt tensioner.

However, the documentation in the mechanic book doesn't discuss the attached pneumatic cylinder. I looked on here, but didn't find any relevant discussion about how to swap the cylinder out, but I'm hoping someone on here can advise me.

In the attached pictures, you can see that:
1) the top of the bolt is a t30 bit.
2) the cylinder
3) having removed the pulley wheel, this is what the bottom of the bolt that holds the piston on looks like

I've stripped the t30 bolt trying to get the piston off. I took it in to AutoZone, and we tried using an impact screwdriver, to no avail. Anyways, how have you all taken this off and put it on your new belt tensioner?