See Tech Video 

A cold reset unlocks menus that have been previously locked and sets all control panel menu items (including EIO settings) back to the factory defaults. However, it does not clear the values in the menu (such as the serial number and page counts).

SERVICE NOTE:

Before performing a cold reset, print a menu map and a configuration page

Follow the steps below to perform the cold reset:

1. Turn the device off.

2. Turn the device on. When the memory count begins, press and hold the check button. Continue holding down the check button until all three device control-panel lights flash once and then remain on. This might take up to 10 seconds

3. After the message SELECT LANGUAGE appears on the display, press the arrow up or arrow down buttons until COLD RESET is highlighted.

4. Press the check button. The device performs a cold reset and then continues its power-on sequence.

5. Check all I/O settings and reset any customer-set device configuration values.