COMPUTER WONT BOOT UP

I was recently installing a video card for my girlfriends computer. After installing, the computer would hang on windows startup, unless I went through safe mode. But then I realized that I needed to disable the onboard video driver….

So once I did that, windows started up fine, but then out of nowhere it shuts off. Since then It starts up for a bit and then shuts off. Turns on and then off. When I went to the bathroom while the computer was open, she cleaned the inside of the computer with one of those dusters that keep the dust on them ( I guess they work with static??). Do you think she could’ve messed up the motherboard? I was thinking it could be the MB or power supply… PLease give your suggestions…

Thank you,
Martin