Laptop won't power up?

I have a Toshiba Satellite L305D (I'm pretty sure that model is right) and it won't turn on. It just recently got fixed about two months ago because the part that connected the motherboard to the power supply input got separated. I think that's what the problem was. But anyway....

I got my mom's laptop battery out of her newer Toshiba Satellite because her's always stays plugged in anyway and mine was dried up. I've been using it perfectly for about a week. But today I let my friend use it.

It was working fine all day until halfway through school my friend asks if he can use my laptop for a second. It's charging so I say he can go ahead as long as he doesn't unplug the charger because I know that's bad for the computer. So I turn around and talk to my friend behind me. I look back and my friend had unplugged the laptop. He was using it fine so I ignored it. Once he returned it he plugged it back in and the screen went black. This happened once before after I switched out the battery but I fixed it by taking out the battery and plugging in the power supply and it turned on. Then I would shut it down, put the battery back in, and it would work perfectly.

But now nothing's working.

I've tried:

-New battery, no power supply.

-New battery, with power supply.

-Old battery, no power supply (I knew this wouldn't work. Wouldn't hurt to try though)

-Old battery, with power supply.

-No battery, with power supply.

Nothing works. No lights pop up. Not even the "it's plugged in" light that is always on when it's plugged in (which is a big majority of the time).

Anyway, what do you think the problem could be? And how could I fix it?

Thank you!