I don't have your unit...had a Pio 531 and posted many "troubleshooting" hints on that unit. Since most TVGOS systems seem to have the same interface and system ops, here is a copy-and-paste of what I saved for emergency.
Some things you could try:
1-First, make sure your cable or OTA antenna coax is connected correctly and securely for your system.
2-Go to TVG SETUP > "Change system settings" and highlight it only (don't press Enter) > Enter on keypad the #s 753159852 (an "X" "I" pattern) > Right arrow to 2nd grey screen > Find "Host Chan" in left column and see if there are #s at right, which may look like 1:0-10. The last full # is your Host Channel.
3-If there is a Host Chan there, remember the # and press TVG button to exit. Save that Host Chan # in case you have to call that station for help.
If NO Host Chan listed, reset the TVGOS by pressing the following #s on the keypad: 653159147. Press TVG button to exit and turn unit off, then on, and reset TVG settings. Don't accept zip code or other choices, rekey and toggle them as if new settings. Wait overnight to see if you get TVG and channel listings for your zip.
4. On the morning after:
If you have TVG listings for days 1, 2 and 8, everything should be working OK now.
If not, repeat Step 2 (only) to check for a Host Chan again. IF you still don't have a Host Chan, you won't be receiving any TVGOS signal, so the only thing you can do is call Engineering at your closest PBS and CBS stations, the most likely stations that might be sending TVGOS signal today, and ask them if they have a Gemstar/Rovi TVGOS encoder and is it plugged in. (The TVGOS provider doesn't let them do anything but plug the encoder in to power and their signal stream and keep it powered up.)
If you're on OTA antenna, make sure the antenna is pointing to your closest PBS/CBS station, since you need the strongest signal. (CBS stations have the option to NOT carry TVGOS, so you may be out of luck if yours if one of them.)
You may have to repeat some of these procedures again if your PBS/CBS station's encoder is not working and they get it working after you call them.
Let me know if you need help locating a tel. # and antenna locations (for pointing direction if OTA) for your local PBS or CBS station...I just need their Call Signs.