CDJ-2000 NXS2 wont start

Ive had my three CDJ-2000 nexus2 since around November of last year...

they have been a bit buggy but nothing terrible until today.

I go to start mixing and one of the three will not complete startup. I hear the disc drive boot every light turns on and there it just freezes all lights on nothing on the screen....

I've tried fully unplugging the unit and still same results on start up ;-?

Is there a master reset or something i can use? its Running 1.55 i was trying to update but i cant even get that far with one of the decks