Yong Heng Diagnoses Help

You should post video. It would tell us more to be able to help you out. Is there pressure in the line? Does the motor making a humming sound? Could be you tripped the breaker. Fan in the back can be stuck. Try forcing the fan to turn with a tool. When you start the compressor, make sure the bleed screw are loose. Check oil level. Make sure you dont use extensions cords. Make sure your outlet can handle 15amps or more.
 
Seem the piston jam. Turn the fan by force until it freely turns. When you turn the fan, it turns the motor and make loosen the piston. Sometime it gets jam and it hung up like that. Use a screw driver to turn the fan without having to open the case. If you cant turn the fan, then you have to open the case to be able to turn it with your hand. 
 
Got it! Turned the fan. Thanks for all the help!!!!!!!!!!

Np. Happen to me once. I just force the fan to turn and it loosen the piston inside the cylinder making it work again. Just remember if you shut off the compressor while there is air in the system, bleed it first. Do not try to turn it back on with air inside. It will jam and motor will hum.