I can certainly tell you what NOT to do. I had a guy once critically glitch on an evasion test and decided he lost his damage resistance roll. I was later admitting I made a mistake and bringing his character back to life. These days I usually say they just really overdid it in their attempt to get clear of the attack and end the pass prone.
One idea for glitching on the soak test is to say that their armor has been damaged, reducing its effectiveness by the AP of the hit they just took (minimum 1) until it can be repaired.
For your example of the glitched adept power, you could always just say the drain is increased by 50%, but that seems kind of boring. Maybe their ability suddenly fluctuates unexpectedly and affects everyone in the room, including foes? That seems to break the known rules on how adepts function, though.
