yes, i am sure u have check things about outlet and socket, and i am not sure what kind of matter happened in your bench grinder, but i can give u a suggestion that you could use your ohmmeter to measure the resistance between the positive pole and the negative pole with the switch keeping on, if the resistance is very small, the tool would be ok, if the resistance is very big, which means ur tool would be broken down, then u could measure the resistance between different location of the circuit to find which parts are failure