WTB: Repair Request Custom DMG Nintendo DS

[Cobra Strike Down]

I have a professionally made DMG with a Nintendo DS inside. I'm having trouble with it as of late where it keeps pressing Start, A and B so quickly it's flipping in menus. A hardy whack with the hand stops it momentarily, but not for long. I can play a game just long enough to get through a lap in Asphault GT, then it starts to go nuts again. I'm assuming since a physical bump makes it alright temporarily, it's a hardware level thing, possibly a crossed wire? Everything is sturdy and well done to the T, so I can't imagine it's terribly hard to work on, but I just am NOT familiar with portables, and don't want to really mess this up further. You can see in the main menu it's perfectly fine. But the other image shows it cycling through menus at light speed. 

If anyone can help, I'm more than willing to pay well for a proper repair. I love this thing, and just want it to work again. I'm a former member here from years ago, but I don't have access to my old email so I can't log in (I contacted Atari Age themselves, and never got a response, so just decided to go new). If eBay feedback needs to be provided as proof I'm a reliable buyer/seller, I'm more than happy to provide (1000+ 100% feedback).