Lenovo G570 - LED light comes on, fan and monitor will not.

Hello to the hardware masters.

A friend's Lenovo g570 was abused in the hands of a borrower, and came back to him with this https://forums.lenovo.com/t5/Lenovo-B-and-G-Series-Notebooks/Problem-with-Hinges-on-G570-model-laptop/td-p/683175/page/11 very common hinges problem. I told him I could fix it, thinking it'd be easy. Well, having forced the hinges into a usable position, I find that the problem is wider.

When I turn it on, with battery or with AC, the blue power LEDs comes on to indicate it's running. The fan tries to run briefly, jerks a little, and then stops. The monitor does not do anything, and shining a flashlight shows no display on it. The LEDs continue to stay on till I hard shut down the computer by holding down power button.

I've tried the turning off and holding down power button 30 seconds etc fixes that are common. Tried with no RAM, with one stick, with the two sticks rearranged, nothing.

I'm almost at the point of concluding it's a motherboard power supply problem that is (hypothesis) preventing the fan from running, and the monitor from receiving power. If that's the case I gather it'd be cheaper to buy another machine.

Do you have any more suggestions for me to try, and perhaps someone can tell me why the motherboard does this?

Thank You.