I think that had the same problem. Everything worked except the total miles display.
I purchased a used instrument console from England. (The cover uses green turn signal lenses vs amber and the temps are centigrade.) By swapping LCD circuit boards and consoles, I narrowed the problem down to the original circuit board. I sent both circuit boards to OdoPro in Littleton, CO.
The memory chip on the original circuit board was bad, so Peter put the correct mileage on my replacement circuit board. He said that he could replace the damaged memory chip and load it, but he would have to order one of the older chips.
He provided excellent service with quick turn arounds and replys to emails. https://www.odo-pro.com/digital-mileage-correction.html
The time resetting means that the power to the LCD circuit board clock is interrupted. Circuit does not go through key switch. You can take the LCD circuit board and apply 12v to the 3 screw holes on the left side and ground on the lower right side to check the operation.
