Jensen Cube screen brightness won't adjust

bergger

I am fairly familiar with how the Jensen Cube brightness works.  We always dim it down to 1 when we go to sleep.  Today while getting ready for a trip tomorrow I noticed the screen on the unit will not increase in brightness.  The surrounding buttons will adjust up or down but the screen appears to be stuck on 1.  With all the blinds closed I can just barely see the screen display so I know it is on.  It certainly appears to be stuck in brightness level 1 which is where I normally have it set.  I have turned off all power to the trailer.  I have also pulled and replaced the fuses for the unit in the converter box and the one on the back of the actual unit.  Has anyone else had this issue and if so any solutions??