Looks like the battery holder may have been replaced which might mean there was some acid damage at some time. Have you tried reseating the game rom? Any problems when turning the game on? Losing setting or anything like that? Do you have a picture of the PSB and the connectors attached to it? Maybe the board was replaced due to a bad connector instead of the board itself.

Just throwing some ideas out there for you to try.

Good luck and let us know how it goes. I've got a few DE games and it's always good to hear what the causes and fixes are.