MT3510 issues (stuck screw head)

So I was swapping out my 12in props for some 15in direct mount props and 1 screw is stuck holding the motor shaft to the top of the motor, I have tried drilling it out with at least 3 brand new drill bits to no avail, it seems to be the invincible screw.

Anyway, I noticed there is a few mm of screw poking out from the bottom (in the gap just above the coils) and thought I would try to disassemble the motor into two halves, but I couldn’t, I removed the cir clip and the gold washer but it still gets stuck on the bearing.

All I can think to do is to use a dremmel cutting disk and cut through the prop shaft base and the screw (completely destroying the shaft in the process) in the hope I can then somehow get the rest of the screw through. I am very surprised at the fact this screw instantly stripped, so I managed to drill a second hole (pictured) and ended up bending the bit on my screwdriver trying to undo the screw with a flat-head.

Does anyone have any ideas on how to get this pesky countersunk screw out?
P.S don’t over-do the threadlock