before posting on here don't you think you should run through standard troubleshooting before looking for help?
Seems you are here just looking for a shortcut to get out of some work. I understand you are stressed and tired, but cmon.
Honestly if i had an issue and didn't do any troubleshooting - just asked for help right off the bat i wouldn't feel comfortable following the advice. Lets say someone tells you it is the motherboard right now, are you going to replace it on that hint and not even check everything else? How do they know any better then you, when none of you have even troubleshooted it. What if it is something completely different and when you receive the board it still doesn't work, you going to tell your customer "a guy on the forum told me to, i need to order something else"?
If you are that stressed and tired maybe you shouldn't have taken the job. Your customers are paying you because they trust you have the skills and abilities to properly diagnose and repair the machine, which you are really not showing at this moment.
Don't take this post the wrong way, but this is not the way you should be handling a customer computer.