I had a computer that I wanted to clean the dust out of. I've done it before and it's worked out fine. So I removed the ram and the drives and the cabling and blew it all with one of those canned air dusters, holding the nozzle a few inches away. i made sure to remove static from my hands by frequently touching metal. then I simply put everything back. Now the power comes on but nothing happens. The monitor says no signal. There doesn't appear to be any hard drive movement. Can you help me fix this? This is a friends computer and I cant afford to buy him a new one.