computer won't start up after dusting??

I just cleaned up the inside of my computer (using a very old laptop right now), I usually spray some dust off inside and vacuum up the dust, making sure not to touch any of the parts or boards. I've done this many, many times before and never had a problem. However this time, when I powered up, nothing was coming up on the monitor. So I tried to manually restart it, and it didn't want to, so I flipped the power switch on the back, and tried again. Now it doesn't even power up.

I tried using a different power supply (it's original one) and still nothing. Now I notice, when I flipped the power switch on the back the internal LED flickers on, then goes off immediately. I tried using my original power supply again, and the internal LED stays on.

Any ideas?

Did I fry my computer?

I'm going to try my master HDD on my very old computer to see if it still works, but I don't think that's the problem.

 

My HDD works fine.

I tried turning it on again, and I got a burning smell coming from the power supply.

I think the power supply fried my mobo.

 

Maybe not, change the PSU as you might get lucky.

 

Tried that with the original PSU, still no luck.

 

Look at it this way:

If the computer is over about 5-6 years old, then it was about time the power supply died anyway. It's a shame that it took the rest of the computer with it, but that is normal for a cheaper power supply like most computer manufacturers use.