PC: BIOS Lights Flashing and Screen Gets No Signal

There was a time where my PC was working and there were no problems with it. My brother meddled with it (he tried to take my power supply, but for a reason that I'm not going to state here, he decided to put it back in and from what I can see, he connected everything properly. And just to be sure I reconnected everything) and now it won't work.
In my PC the BIOS is just a series of lights rather then sounds. So when I turn my PC on, the lights start lighting up in this order (when the light is on it means there's something wrong with the given part):
CPU -> *pause* -> VGA -> Boot (it stays on it until I turn the PC off)
The screen is also not catching any signal. I tried taking the BIOS battery out and putting it back in and reconnecting every cable inside the PC, but the problem persists.
I appriciate any response that tries to help even if it won't be able to.

My mobo is: MSI A320 Pro-VD/S
If you need any other information just ask.
Or if you know any other thread talking about the same problem, please post a link to it in the comments.
Thanks in advance.