Most vehicles would respond to a “hard boot”, take the battery off and reconnect it and it would start.
Of course, probably 1/100 city folk would noodle that out or know it...
You dont understand how an EMP works. It burns out the tiny runs (wires) in electronic chips. It does so by creating a charge in those runs that physically overheats them and causes the to be totally and irreparably destroyed. Reboot is pointless. It is akin to rebooting a brick. You can hook jumper cables to it but it is still a brick. A doorstop or a paperweight perhaps or fine for throwing at your TV but applying electricity results in zilch.