TRY a software reset.

Press and hold the opt button, the first multi function button, and the third multi function button all at the same time. The multifunction are the ones at the bottom of the display.

OPT, 1 , 3


If it doesn't respond to that then i'd try a good ol hard reboot.

Disconnect the negative battery cable from the battery to make sure there is no power going to the radio at all. Let it sit for a few and then reconnect the cable. Test the radio...

Hope one of those helps.