O2r crashed after doing a reset

[DigiMix]

I have two O2r digital mixers, and did a reset on #2 by turning it off, then holding down the left curser and turning it back on.  Rather than reset, it did nothing, and the only evidence of life was on the screen with the O2r display.  Previous to this, I had done a recalibration of the faders by turning the mixer off, then turning back on with the Enter button held down.  I think it was this action that caused the mixer to go to la la land.  Is there another procedure to try before making a boat anchor out of this mixer?

Today I unplugged the mixer and removed the backup battery, then turned it back on.  It lit up; then I turned it off and unplugged it again; replaced the battery and then plugged it back in and turned it on.  Now I'm back in happy land.