I have had the issue several times with my PSR-500. A few things to try.
1. Any reception if you press weather button? If not try #2.
2. Do you have an external speaker that you can plug into the radio to see if you get sound? If not try #3.
3. If you use Software to program (WIN500, PSREdit, Butel) make sure you have a copy of your configuration in the software. Then do a Factory Reset on the radio (turn on radio and press 0, 5. Clears working memory and runs eeprom memory test). If that does not work try 4.
4. Smack the side of the radio case sharply (not kidding). This works on my 500. Apparently a card is not seated properly or something else is loose.
Hope this helps.