It's been fixed. For posterity, I'll post what the problem was.
I borrowed another tivo and it was still the same, so that told me it wasn't the tivo.
Verizon then sent a new cable card and it still didn't work, same thing No Signal (V52), with either tivo.
Finally verizon sent a tech, and when he saw our ancient motorola bpon ONT, he immediately went to replace it.
He didn't even bother coming into the house first to see the issue with the tv.
He also went down the street to replace a splitter (I'm assuming optical splitter?, because it's fios)
After that, everything was working again.
Interesting that it was the ONT, because we also have phone and internet, and they were working. Only tv didn't work.