Irb 6400r m2000 mode switch fault

another day another problem, this robot lost all sync,programs ,i/o's etc over the weekend most probably during a power outage.when trying to sync it i turned key to manual but it doesnt seem to acknowledge this and wont jog saying 2 channel fault.turn back to auto and no change of operating mode message on screen.swapped pendant and still the same.all leds are lit on panel board even when key is on manual.swapped panel board and still the same.has anyone seen this before? Could it be faulty contacts on key switch?