This control has 7-segment LED's, and to get all of the segments to light up (number 8 ) you have to feed voltage to each segment individually. This is controlled by a microcontroller, or a decoder chip. I'm guessing the board is bad, and maybe an element shorted out and pulled too much current through the board and cooked it.
I could see an incorrect power voltage making the display do weird things. Check your voltages, and don't forget to test voltages with respect to ground.