Why does my Altivar drive have no display?

Issue:
Why does my Altivar drive have no display?

Product Line:
All Altivar drives
 
Environment:
Display doesn't light up
 
Cause:
n/a
 
Resolution:
Measure the input voltages (phase to phase) at L1, L2 and L3
Measure the DC bus at PA+ and PC-
Measure the +24v and +10v supplies. Measure to COM, not ground.
If the DC bus is ok, then could be a problem with the Main Control board and/or the Power Board, of the drive.