4slot, only boots to I/O test mode.

That 4 slot is now no longer even booting to the only mvs cart I have. It's only booting to the i/o test screen.

I may have accidentally put in the cart backwards, would that break the board? >_>;

backwards?
Did you insert the cart backwards into the motherboard?..For this to be possible you'd have to have the mother boards shell off..(yes)
I'm not sure if it'll pop the board.....you may have fried the cart..

So when you insert this cart you get the crosshatch Screen..?..what happens with no cart inserted..?

Have you tried the other slots..?

yes. no cart, i get no boot

cart in in any slot, I get cross hatch

My only answer is to do a search "cross hatch" as a ton of topics will come up..

I've yet to find the problem with a 4 slot board I have that goes right to cross hatch..

Booting the system without a game will always give you the hardware test "cross hatch".

When you inserted the game backwards, it is conceivable that the game was damaged. I have accidentally done this before without any damage to game or system (my 4 slot does not have the upper shell).

Try checking the +5v at the jamma connector when it is powered on and connected to the MVS. Also, make sure that the game is well seated in the slot. Try inserting it, and then backing it out of the slot a bit to make better contact.

good luck!
-DT

Just an update. Hate to bump an old thread and all but...

Putting a clean MVS AOF1 cart in place of it makes it boot fine, I still have wierd sound problems though.