4 slot Ram bank error

Okay, this is a new one to me.

I recently sold a nice cab with a four slot board in it. I had never had any trouble out of this board and as soon as it is gone I get an email that it is giving problems.

First it will not read a two slots, then it will not read one slot, and now it comes up with a white screen.

So I ask to have the board shipped back and as I am going to send another board that I know for sure works as I am pulling it out of my best favorite cab to replace this board.

Now I've gotten the board and when I put it in. It comes up with a off white screen with white letters you can only just see that says,

Ram bank error..

Then under that I can't really read it but may say switching or something and some numbers.

Anyone know what would cause this board to just go crazy like that. Also any ideas on what may be done to fix it.

Next I am going to send this guy a working board and I don't want it to end up like this one and I was wondering if the voltage got out of adjustment or something when he had it shipped and maybe that was a problem but I could just be way off.

Any help please.
Thanks.

Post a pic of the error message plz.