Hot water will only run on "Hot" setting

WELL, let's use a little logic here. There might be 3 wires (or maybe 4) going to your water valve, 1 to hot, 1 to cold, and 1 (or 2) to both. Since hot water runs in one case but not in warm setting, the valves are working, and the wires to the main PCB are OK. There must be 2 separate circuits that control the hot & cold wires. That would place the problem on the main PCB.

Now, considering the $400. + cost of that board, you might want to remove it and check some things. Start by resoldering all the connector pins on the PCB. Those Molex connectors especially can develop cracked connections if they were flow soldered and not post flow inserted and manually soldered. Those cracks are near impossible to see except under a glass.

Then test relay coils, diodes, opto-isolators, and transistors.

If you can find nothing, unless you can find a used PCB at a reasonable enough cost, you may want to consider a new washer, since only the PCB might have a short warranty, whereas the whole new machine will likely have a longer warranty.

Then again, it may not be that PCB, but I don't see anything else.