The little nubs that push the handle down to engage the power switches had worn down too much. No power!
I measured out the internal dimensions of the cavity in their injection-molded handle part and whipped up this insert to get it running again.
Print off part
Trim off excess plastic on printed part if it doesn't quite fit. It's a tight fit! Optionally, download the OpenSCAD file and tweak the dimensions manually for a better direct-print fit.
Push insert into handle.
- Wash dishes!
...or don't if it turns out the electronics are too far gone. Fixing/replacing that with some Open Source Hardware is for another, future entry.