If you have your custom programming saved on a computer to which you have access, you can release the unit from test mode in which it is stuck by following this procedure:
1.Open up the MX-800 editor & run a live update, if available. Load the custom programming for the failing unit into the editor after updating.
2.Remove 1 of the battereis from the unit. Press the light button several times until the unit is drained of power & the screen goes blank.
3.Press & hold the "MAIN" & "ENT" buttons simultaneously. Continue to hold these buttons while you reinsert the 4th battery.
4.Continue to hold the "MAIN" & "ENT" buttons while the unit performs the self-test & the "running man" icon proceeds from left to right along the bottom of the screen until he dissapears. Release the buttons once he has disappeared.
5.Connect the unit to your PC & download the custom programming. Ignore any error messages that do not inhibit continued downloading of the profile, as it is common to see error messages at 25 & 50% completion while still being able to release the unit from the test mode. Repeat this process at least 2 more times if you receive an error message that stops the download process.
The unit may still have a failing PCB that needs to be replaced, especially if it fails this procedure 3 times.