After a lightning strike, flood, nuclear blast, or other catastrophic disturbance, the 372 may become inoperative if the data stored in its EPROM memory has been corrupted. The 372 can be returned to its factory default state by performing a master reset. To do this:
1. Unplug AC power
2. Press and hold in the EXIT and CAL buttons.
3. Reconnect AC power.
4. Let go of the EXIT and CAL buttons.
Now the LCD screen will display “EEPROM defaults restored” followed by the software version number. After doing this, all previous setup and calibration data will have been lost and must be re-entered as if it were a brand-new installation.