I blew up the exact same Y sensor while doing maintenance on the nozzle (and fixed it by replacing the RAMBo). I think the heater resistor insulation together with the thermistor hold plate is a bad design choice of AO. I hate to repeat myself, but nevertheless feel obliged to mention my solution.
I got rid of the lower part of the thermistor hold plate and made sure the heater resistor leads are completely isolated from the hot-end by covering the bare leads in exhaust repair cement.
And yeah, I know general advice is to shut down the printer on hot-end maintenance and never touch it with conductive brushes. It’s just too easy to short the heater resistor wires IMHO.