Audio Systems: RB1 Nav Radio Display, 2004 grand cherokee, radio face

Question
I am buying a used 2004 Grand Cherokee with the RB1.  It seems to work perfectly.  When I got the vehicle checked at the dealership, they noted that the display sometimes took several seconds or even more than a minute to come on.  During the "black out" the radio was audible but none of the control buttons on the RB1 face worked.  I can only create this problem by turning off the ignition and then immediately turning key to acc.  When I restart the vehicle, the display powers up within a few seconds and all works fine.    Is this normal or is it a sign the unit is failing?  How can I check to see if the unit is beginning to fail?  Thanks.

Answer
Radio is going bad , i seen this in a a lot  jeep dodge crysler vehicles  when the radio is on for a few minutes or gets hot part of the radio face stop working , i have no idea where  the problem is but i manage to repair a few  by removing the face of the radio
and resoldering all the contacts, it is just a cold solder i just don't know where