If it does not remember the DCS setting after shutdown, the battery is no good or the harness is bad, or the board is going bad. You say fresh battery what does that mean? Try a new alkaline for testing purpose. I would also disconnect speaker at 2 pin. Speakers on these go bad, along with older batteries. You may also have a short or a loose AC power wire on the trucks, red or black. Bad pickups even though oiled (you can't see corrosion on pin inside roller) can also cause issues. Wheels need to be cleaned with wire brush.
Of course this is a PS-2 5V I assume from 2002, and that board could be having end of life issues. G
