No Video on TIVO after update.

I have a TiVo Series 2 Toshiba SD-H400 box. I only get TV through over-the-air broadcast and an RCA converter box. Everything was working find until Saturday morning when I found the machine frozen. I understand there was a major update overnight. So I did a restart of everything. It rebooted nicely except for one thing: there was no video. I got to that screen that asks "Do you see a picture?", I had no picture (or sound). Just blackness. I have video coming from the BNC connection on the converter box into the TIVO machine. I unplugged it from the TIVO machine and put it directly into the TV and there was video!! I replugged it back into the TIVO and still nothing. I rebooted a couple more times. Nothing! I found TIVO literature on how to set up your machine with a converter box and followed it religiously - even using composite cables now instead of BNC coax. Still nothing! Does anybody know what's going on? What did the update do that could mess this up? How do I fix it? I can still watch TIVO recorded shows just fine. TIVO also downloads the new guide just fine (over WIFI). I'd really really appreciate it if somebody could help. Thank you very very much.