You have a full teardown to perform. With your description my expectation would be to find a seized bearing at best and a ruined piston/cylinder at worst, maybe with a busted ring, but cooked for sure. Since I don't know the machine I don't understand how it could run at full throttle for a minute without someone spraying? Has the throttle had problems auto-adjusting before? I wouldn't fault the user.

DON'T try to test or adjust the washer with it behaving this way. When you close the nozzle and the engine dies, it almost always is a "dead head" condition. Most likely an unloader issue, but could be plugged bypass or such also. Regarless of what the problem is, it is extremely dangerous. Depending on the flywheel weight of the engine, pump design, etc, you might see 10 times the rated pressure of the unit as a spike when the gun closes. A common failure is that the discharge fitting blows out of the pump and the hose turns into a huge whip as it deflates. If you are not familiar with how all the parts work, you probably should take it to a pump or washer distributor/repair station. It just isn't worth getting hurt.

It sounds like a spring may be missing. I'd try to find an exploded parts view of your model to see what's supposed to be in the gun. Try www.pressure-washer-parts.com

My wife bought a pressure washer last year. She did all of the pressure washing stuff and I didn't pay any attention to what she was doing. It is a Craftsman 2.2 GPM PW Model 580.752040 For some reason the garden hose will not disconnect from the water inlet. I have attached the wand and held the trigger to release all the air and nothing, plus I think she stripped the plastic nut pretty bad. Should I just buy a water inlet kit and replace it. Any suggestion on what to do next? Thanks