TRY pulling the stem all the way out and then press it VERY gently to see if if moves. Be sure the rest of the watch knows which half of the day you're setting it for, otherwise it will move ahead at noon instead of midnight.
You mean to say that your watches is not working after 5 minutes ? is yes the answer is you have to visit any Citizen service center near to you and ask them to solve the problem. Thanks for posting question
I'll need to know exactly which watch it is as there are a number of different ways of removing backing plates. Photos of the back of the watch would be just as helpful.