Sega Genesis Model 1 VA7 No Picture and Singing the Song of Its People

So I have a Model 1 VA7 Genesis that does not display anything and plays a haunting melody of games long played, which are played no more. See video to be moved, emotionally, and digestively.

Oh, and sometimes it doesn't always give the black screen with the sound. Sometimes when I turn it off, I get no signal but the led does come on. In that instance, I have to turn it off and back on again, and then I get the black screen and screeching.

https://www.youtube.com/watch?v=qXAlmeUu...

What I've tried:

Checked IC11 near the video and power ports to see if VCC1 and VCC2 were getting 5v. They were.

Checked the voltage regulator to see if it was outputting 5V. It WAS NOT, so I changed it with a new 7805 and now it is outputting 5v. Still no change though. :(

Checked continuity between the cartridge slot pins and the pins where it's connected to the board. All pins appear to be connected. Reflowed pins just to be safe and rechecked. Same issue.

Reflowed all the pints on the video output and power connector, no change.

Pumped the video out signal from IC11 directly into video cable just to see if that would tell me anything. No change.

Checked a few caps near the video output, they all seem within spec more or less.

Tried multiple power supplies that I use with other model 1s with no issue. No change.

Next, I plan on checking the rest of the chips to ensure they're getting the power they need. I'll also be checking all the traces from to chips to where they go when I feel like I need something boring and tedious to do. But in the meantime...any thoughts?