I would take the case apart(if possible) and see if you find anything obvious like a capacitor that has exploded(for lack of a better term) and that all the wires appear to be connected properly. I've got a Uniden SC150Y that quit working after being left out in the garage for a longtime(took the thing apart and still can't find anything that looks like a problem). The solders could have broken loose on the board, the capacitors on the board could have gone bad, unfortunately the possibilities are pretty endless and the only way to know what the problem is would be to get a voltmeter and check from the source of the power down every connection on the board to see what your issue is. Some cold-solders are almost impossible to see(that is where the solder either never made contact with the board or where it has broken loose.)
If the scanner has a lot of sentimental value then you could take it to a electrical repair shop, but the cost of repair(assuming it isn't just a loose wire) would probably cost more than the thing is worth.
Also, before you go putting the thing in the dryer and banging the crap out of it, just pop open the case(remove screws or whatever is keeping it together) and put a blowdryer on it. No need rattling anything else loose inside the scanner of destroying your screen.
