The second reply above has a very close duplication of the “cold boot” instructions.
I would add that after the f/w install the process requires disconnecting the USB cable and cycling the power to the Bullet. But a quick on/off isn’t going to do it… I needed to power off the Bullet, give it a count of say 10, then power up. If it boots up ok, then connect the USB. I have a power distribution box with a breaker for connecting the Bullet to make it easy. There were frequent f/w changes at that time and fussing with that jumper (yeah- a paper clip; still in the tool case) while trying to plug in the Bullet power cord was about one thing more than I could handle safely.