2005 REC model NAV unit reset required

Put in an updated NAV DVD and my REC radio in my 2005 Dodge Magnum, did
a software update, then did it again, and again.

After the 3rd try the radio went to a black screen, not even the
backlight.

There is no display at all now. The radio will load a cd, and play it
from the first track onwards, but I have no control over it other than
volume. I can not change between cd and AM or FM.

All of the buttons along the bottom are unresponsive, I can not go into
NAV mode and there is no display at all.

Does anyone know how to reset this radio so it will re-load the
software from my old DVD?

I have tried removing the radio from the car for a couple of hours, but
still no go.

There is no visible emrom chip or battery on the board, and no visible
reset button.

I know this radio is made by Alpine if that helps any.

Chrysler part number P56038646AL

I added this to the car after I purchased it so there would be no
warranty on it, got it off of EBay.

Worked for over a year, just stopped when the update disc, which I
believe is damaged or data corrupted was put in.