If only one of the screws is stripped, you can try removing the other screws, desolder the motor from the ESC first. Then instead of trying to rotate the screw with your screwdriver, hold the stripped screw with you thumb and rotate the motor instead of the screw this time. Torx Bit M...
4pcs HSS Double Side Drill Out Damaged Screw Extractor Bits Set Guide Wood Broken Speed Out Easy Bolt Stud Stripped Removal Tool Features: Removes any screw or bolt (Phillips, flat, hex, painted more) Durable hardened steel construction