If any piece of electronics has fewer than 6 buttons and doesn't work, it's always worth turning the power off, holding all the buttons down, and turning the power on again. Seriously, saved a £100 bit of physics kit today.
Why <6? Fingers.
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I'm curious what kind of device that was. I also wonder how often that would actually break the device, by virtue of e.g. badly designed bootloader entry.
@robryk SEP energy meter. Known issue where a stray live lead brushing the metal case can screw things up.