Jensen VR187 radio/backup camera observation monitor won't work

We have a 2007 Bounder Diesel Motorhome equipped with a Jensen VR187 radio/backup camera with color observation monitor. Once before the radio wouldn't turn on nor would the backup camera work. (Screen wouldn't come on at all.) While in for maintenance, we had dealer look at it. Dealer fixed radio/camera. Told us that they simply "reset" the radio. We have found the manual for the unit online, but can't find the term "reset" in it. Anyone have any ideas?