More importantly, figure out what you did wrong before you break another motor lol
Run both wires to the back end of the grip, make sure the longer wire is off to the side of the hole.
Press your motor all the way down before putting the end plate on to make sure it's meshing with the gears, otherwise you might tighten your motor right into a gear tooth and take out your gearset as well.
And now that you have a new motor, you'll have to learn how to adjust motor height.
Back off the screw on the end plate FIRST.
Then install the motor.
then tighten to screw until you feel the motor is at the end of it's travel, do not tighten it, this may bend the shaft.
Back the screw off one and a half turns.
fire the gun, and tighten by 1/6 of a turn at a time until it stops making that whiny gear clacking noise. If you hear a high pitch squeal, you've gone too far, back it off a bit.
Getting your motor height adjusted correctly is extremely important for the durability and performance of your AEG.