I did see that board....but would it work with my machine? I guess it would right?Unfortunately replacing the micro is not an option even if you knew the generic part number.
Before you junk the board just probe the pins of U1 and satisfy yourself that the device is getting what appears to be a sensible voltage on one or more of it’s pins, excluding pin 5, that could be VCC.
It could be 3v3 or 5V, I believe you thought the board ran from a 3v3 supply, check for this on U1.
If that looks ok then the processor port on pin 5 is probably defective and it’s either purchase a replacement board or junk the cooler.
To give you an idea of replacement cost ebay has a very similar board labelled Howden wine cooler display control board 082641452 for about $42.