ONX-580 will not power on

My Viavi ONX-580 One Expert will not power on regardless of whether it is on battery or AC power.

Remove the AC power and lay the ONX display side down. Loosen the four large screws securing the DSL module to the ONX and remove the DSL module. Remove the single screw securing the plate of the battery compartment and remove the plate exposing the battery. Unplug the battery connector and remove the battery. Replace the plate over the battery compartment and try to power the unit up on AC. If the unit will not power on then the unit and power adapter should be returned for service. If the unit powers on then power down and remove the AC power, reconnect and reinstall the battery. Reattach and secure the plate over the battery compartment and then reattached and secure the DSL module. If the unit will not power on with the battery installed then the unit should be returned for service.