My Jensen JRV212T mysteriously developed the same "Blank Screen" syndrome. I have tried every trick found and still have the same problem.
I've decided to scrap the Jensen & install a Sony Headend Unit (Sony XAV-W650BT) $299.99 from Crutchfield with DVD player, rear camera input & all the other inputs I use - Front auxiliary, Rear auxiliary, USB & Bluetooth.
To handle my rear view & side mirror cameras I am adding a SV-900.CSB
Multi-Camera Switcher from sonicelectronix.com for $69.99. This unit has the triggers for turn signal input, back up input & a wired remote to allow manual camera selection. I am buying one more to keep on-board - just in case. $70.00 is a bargain compared to what I would pay to arrange a fix on the road.
This will allow me to choose any automotive Stereo system that will plug the dash hole & provide for a single video input (Commonly available) and the other inputs I want to have. In a pinch, I could stop in any Wal-Mart and pick up an emergency replacement unit (maybe without the frills - but with the driving necessities) for a couple hundred dollars.