This thread gives some history and pics. Someone found a closely matching service manual, which is here:

how-to-repair.com/…/Beko-WMB61431B-Washing-Machin…

That goes to the error codes, which implies that I was reading the error codes upside-down. The machine apparently has error code 18. It means the “load is imbalanced”. How does it sense that? There is no load in it at all. But it’s trapped in an error state that cannot be cleared.

Am I missing something? Because this is outrageous. AFAICT, all components work. But the control board thinks there is a fault. And there is no way to clear it and force it to run. Page 86 of the service manual says:

“Explain the customer the following unbalanced load preventive actions.”

IIUC, the previous user ran an unbalanced load many times in a row. They retried running an unbalanced load enough times that the machine entered a locked state to protect the machine from damage. But this service manual does not give a way to reset the machine. Am I fucked?