Yes they are installed pretty tight. You might be able to grind your T50 bit flat on the end to remove any radius, use a hammer to get it right down in the bottom of the bolthead, and try it (by hand, not power) again.

 

It fu$&ing sucked.
After many different trials. I won’t bother you all with them.
The successful one was, heated the bolt with butane torch for like 1+ min, (if you have something bigger probably would be less) until smoke came out…. Probably Loctite….. impact wrench…. Finally came out.

its stripped pretty badly. I was pleasantly surprised that I didn’t have to use the revered drills to extract it out.

 

Hopefully just the head is stripped. Did the bit survive?
At least you didn't have to weld a nut on it!

 

Yeah the only “real” damage was just the bolt head. Everything else survived.

The second one came out easily with just the breaker bar, after a long heating period…