Hard reset from front panel:
1. Hold SYSTEM and press CANCEL.
2. Press ENTER. (follow screen directions)

If screen/buttons do not respond:

Turn unit on and off 8 times. (Turn on, Count "One-thosand one", turn off. Turn on, Count "One-thosand two", turn off, etc. After the 8th time, the unit will be reset (All DP series)

Diagnostics:
1. Hold SYSTEM and press ENTER. (follow screen instructions)