sounds like you having the same issue as many others including myself. the video not showing up is probaby step one of many more issues to come. mines also would show no video and after some time it would come back. until recently, its pretty much dead now lol.
you may have a bad motherboard. doesnt sound like the fan is the issule or power supply. as for the usb not working that also points to the motherboard. sooner or later you may just have to buy a new one of fork over 150 to sony to fix it... i hope i'm wrong and you'll able to fix it.
if you start it up and no video shows try holding down the power button until you hear a beep, thats the video settings going back to defualt, should help with the no video showing up when you start it. hope this helps