I have a few DD PCBs that I have been wanting to go through. I just won one recently on eBay and had another one from Xmas time. The one from eBay was untested and missing the ribbon cables.
I plugged it in and got the 63701 error. Switch out the CPU board with a known working one and the problem went away, which confirms that the problems is on the CPU board. The TMM2015-10 at IC22 is a common fault on these boards, and usually the first thing I replace when I get a 63701 error. I piggyedback a good RAM, and the game booted up fine. I switched out this IC and the game is now working.
Plugged in the other board and also got a 63701 error. Replaced IC22, and got the same problem. I need to dig a little bit deeper when I have a chance. I did switch half of the board and also noticed that there is some sprite problems along with the 63701 error that needs to be addressed.
The nice thing about a socket on IC22, is it allowed me to test some of the RAM chips that I pulled from a junk board.
