bad X1 main box?

I'm experiencing problems on the main set top box. When I first cut my TV on, the picture is scrambled. After a minute of this, the tv will switch off and reboot. Sometimes a piercing noise comes across as it reboots. It does this for 10 or 11 tries before I get a picture. Occasionally it will go out while watching. Process repeats but doesn't take as long to get picture. Sound comes in fine. My first thought was bad capacitors in the tv, so I hooked up a Firestick to the TV and it worked fine. I then replaced the Hdmi cable with same results as the old one. I discovered that if I watched the Firestick for a while then changed over to the cable source that it usually came on, sometimes on the first try but usually after a couple of tries of switching back and forth. Still occasionally goes out while watching but switching sources will bring it back. I have tried switching HDMI ports on the TV, checked coax connections and tightened, no difference.  Other tv locations are working fine.  I'd like to try a different set top box but our local store is closed due to CoVid19. There is an amplifer on the line but since other sets work fine I can't see that as a problem. Any suggestions? Or do I just cut the cord for good?