No, different set of batteries.

Were you using the same set of AAs in both game boys?

I'll probably contact the seller about a possible refund.

Both game boys though, common point between the two is the cart...

You can try for instance to plug a game cartridge and see if the gameboy is still getting hot...

I doubt it was caused by the cartridge.. its more likely you've got a short circuit or something on the Gameboy itself. Hence the reason it rebooted. Do you normally run it on batteries or from a mains power source?

I've had my gameboy do the weird numbers thing before when someone turned my charger off at the mains with my gameboy still on. I fixed it by going to load a different song and making sure I didnt save it before loading the new one it seemed to revert back to its previous save state and fixed everything try that.

These things happen to people all the time, its old hardware.

Maybe time for a new cart

It just started happening yesterday. the GBs were working perfectly before.

Maybe wait to see if anyone else has a similar setup to yours, could be that the mods plus flash cart are using more than the power supply can produce. Unless this has only just started happening?

biverted backlight with prosound on both.

Any mods on the GB? Backlight?

very unusual problem. Sounds like something is up with the cart

around the center ish, I'm only going by memory at this point cuz it happened like 30 mins ago.

EMS64? I wouldn't think the power supply in the GB could provide enough current to damage anything downstream from it which would suggest it is the source of the smell. Which part of the cart is getting hot if you can pinpoint it?

The gameboy is producing the smell, and the cart got a tad hot.