Newish diswasher won't drain after some efforts. Any suggestions?

We got a Whirlpool last summer. Yesterday it stopped draining. Washing works; draining doesn't. We removed the standing water. We made sure the disposal was clean. We checked the filter and line for obvious blockages. We made a baking soda paste, poured vinegar into it, and 15 minutes later poured boiling water into the base.

When we press Drain (Cancel), we initially hear a sound like something is going to happen. Unfortunately, the normal sound is quickly replaced by a light clicking/buzzy sound at the bottom of the dishwasher, which is followed by nothing. The water doesn't move.

Any suggestions for possible solutions or guesses as to the problem? Thanks very much.