Did you replace all the relays with the relay board? Check where the wires go into the valve coils (fast and slow). They get brittle and can become intermittent. Make sure the up level strainer is clean. If the problem is intermittent, reading continuity means nothing. Pull the switch tree, clean the contacts, inspect the wires thoroughly. Breaks inside the wires are common. Cut, strip and re-terminate the wires in the screw terminals. I just recently had a bad connection there, the bare wire was under the terminal, it was tight, wouldn’t pull out but was just not conducting. I’ve also seen the MTA plugs from the switch tree to selector cause MLTs. Motor thermal and overtemp switches. You have to be thorough or these can get out of hand. Any info you can get from customer or other mechanics will help a lot. Was the motor running, does the car move, if so where does it stop, etc.