Is there any noise to speak of, like the door lock clicking?

No noise. It’s completely silent. So I disconnected the garden hose because if it does not even trigger the water inlet solenoids then it does not help to maintain water pressure for future tests.

User manual seems to be pretty readily available online,

I’ll have another look, but I generally ignore the dedicated third-party manual websites as they are just time-wasting enshitified rabbit holes. If I am convinced a service manual is in one of those walled gardens, I might go through all the boot licking hoops and do a dance to get it.

In any case, I appreciate your feedback.