This is the problem of the "safety-at-all-costs" electronic switches to ensure NVR etc.
They have transistors and diodes and those things can not only go poof, but also have unforseen interactions while dying but not-dead yet etc.
This means that ensuring "the switch is off before plugging-in" is no longer enough, actually it is harmful as it creates a false sense of security. The only safe way these days is to learn to hold the tool securely any time one is plugging it in. Ah yeah, and do not leave bats in the tools with protruding blades and such.
In the old times there was a physical switch while it would possibly stay powered if had a mechanical lock engaged. But there was no way the tool would "power itself" if it was not under power the last time it was plugged ...
