aircraftrecords cites:
(at VYR)...The coneheads (avionics mechanics) were messing with CB's during run and pulled a breaker that put the aircraft into flight mode...
Presto! Engines to flight idle, no reverse thrust, no brakes & no steering... It jumped the chocks so fast the mechanics in the left and right seats didn't even know what happened (they didn't even know the coney's were messing around with the CB's)...
There have been other dire events associated with uncoordinated pulling of CBs - like disabling overspeed protection of engines
Best practice is to have a thorough briefing before any such action.