Laptop Repair section/topics? Testing MB

Couldn't see where to place this as I don't see repair or anything like that on this forum? I'm not getting much response on this in the Lenovo forum, so if there is a repair section for this, please move this there. Anyways: How to test to see if my MB works or is bad? Only test I did was it wouldn't turn on, no lights or noise of any kind. Assumed it was a bad MB.

I got a used mother board off eBay thinking that was my problem, but it didn't work so I sent it back, the eBay guy who I got the MB from refunded all my money via paypal then told me this:

Maybe my MB isn't bad after all? How can I test for that. I was thinking of testing the laptop as a barebone system, but how would I turn it on without a power button to push, or does it just come on once I plug in the AC adaptor.
The bare bone system setup I have:
Wood bench
1. Motherboard
2. CPU with the cooling module.
3. Known good memory module.
4. The power button board.
5. Known good AC adapter
So, how do I turn it on without the power button?

I just hope I don't have a bad CPU?
Any help appreciated as I really want to fix this laptop.

Update on what I did before with the used MB off eBay... when I tried to turn on the laptop, I got a blinking orange light, that eventually turned into a white light. No power light or fans or any other activity. Wouldn't that light rule out the power button & DC jack?

Laptop in question is in my signature.

 

@jack53 some light usually turn on when dc jack is plugged. It doesn't mean motherboard works, just the fact that it gets power. Some systems won't turn on unless fully assembled, with all screws in place - but that's pretty rare.

 

What started all this was one day when I went to turn on the computer, nothing happened, no lights, no fan noise, nothing. (Battery was fully charged at the time too.) The MB I got off eBay, nothing worked either except for the battery light that came on. That was it. I'm trying to find out if it's the MB or something else.

 

Could use some help here! The above asked question was asked over two months ago. I really need to fix this laptop!

 

@jack53 try unplugging battery and PSU, then unplug power board, and attach psu - it may fire up. try with battery if it doesn't.

 

Done that several times... no joy. It's possible it's something besides the MB as I got one off eBay from a reputable guy and when it didn't work I sent it back, he refunded me and when he tested it, he said it worked fine.

 

Asking again... surely someone here has done this before? I have a $800 brick here that needs to be fixed.