PRO-164/etc
That is a catch all message when the scanner does not have anything to scan. It can happen when, for any reason, the scanner is no longer programmed. It can happen when you've uploaded a new file, but do not have anything turned on.
Other than the scanner being totally unprogrammed, the most common scenario is having no banks selected. To toggle a bank on & off, simply press its number (0 to 9).
However, even if you have a bank on, all of the programmed frequencies in that bank may be locked out (or the bank does not have any programmed frequencies).
What I'd do is press MAN, then press 0 0 0 MAN. Is there something programmed there? If so, is that channel locked out? Press UP to go to the next channel. Verify you have something programmed and not locked out. If you do, then press SCAN. If you see the locked out message, press 0. What happens?