I've got a relatively cheap ohm meter, and not the "power windows" beep. But, basically, probes not touching yields an "L" on the screen by default, touching the probes together yields some changing numeric values (I was calling "flux" in the signal), and a "working" fuse that also has continuity also yields some numeric fluctuations (which I'm taking as "resistance") vs a non-working fuse (which also shows "L").
On another note, I think I found my issue based on your inquiry about the relay ("NO" labeled on the relay, btw). I hit the button for the malfunctioning jet, and then tapped on each relay a few times. Eventually, tapping one of the relays cause the pump to turn on! After a youtube video about replacing a relay, I see that I'm probably now up against replacing the relay (~$10) vs new motherboard (~$450).
I've got a bit of a learning curve in the area of electronics, and any advice would be appreciated. But, I believe I'll need a solder wick for the removal of the old relay, and a light solder gun (I have a heavier one that's likely to hot for a motherboard), and the new relay.
Thanks for the help!
-ak