SNES Powers On, no games work with one odd exception

So I've run into a strange issue. For many years my SNES has worked fine, until I noticed one day that none of my games were booting. The only cartridge I could get to boot was the Super Flash Cart sold by Tototek, which gets to the menu, but no further. For the rest of the games the power light is coming on and the screen will briefly flash but stay a black screen. No sound is output.

Things I've tried already:
-Cleaned system, cartridges and slot
-Bent the slot pins slightly to get a better connection with cartridges
-Left system powered on for a few hours and hit the reset button.
-Checked the DC power supply's voltage with no load. Looks fine.

I've read a few forums(including this one) where there's some passing mention of this issue but no solution is ever posted. Has anyone ever figured this one out? Or at least have some ideas of other things I could try? I was already thinking about changing caps or disabling the lockout chip as a next step, but I was hoping someone may some thoughts.

 

So on a suggestion from a friend I tried out a game genie. To my surprise it also started up much like the Super Flash cartridge. I also could hear the gunshot sound, so I know audio still works. However just like the Super Flash it doesn't work for long. It basically get the title screen, fades out and that's it. I tried moving the d-pad in case it's something with the video, but it's definitely frozen. No sound effects or anything. Video signal is still coming through at that point as well.

 

Try different A/V cables?