Help needed badly... pc turns off before it could even flash anything

good day! i am new here so my apologies if ever i had posted on the wrong section...

so here's the situation. my friend had a pc whish is only 1 year old.

pc specs: AMD Athlon 64 x2
ASRock motherboard (not really sure about the mobo model but what's written on the board is AM2+Quad Core CPU)
1GB Apacer DDR2
160GB HDD SATA
128MB GeForce 6600
450W PSU

one day it just wouldnt boot, all fans are spinning, all leds lit up but no beeps of any kind.

what we did:
1. cleared cmos
2. changed PSU with a working one
3. reseated and changed RAM
4. took off everything except the essential components (CPU, RAM, PSU, Graphic Card)
5. Changed Graphic Card with a working one
6. reseated cpu

all of these did nothing so we concluded that the mobo is the culprit here so we decided to buy a new one.

the new mobo now is an ASUS M2N68-AM SE2. so we inserted the cpu (reapplied thermal paste and all), and other essential components. the problem now is that when we turn it on, the led lit up, cpu fan starts running but just for about 1 second and then turns off (led turns off, cpu fan stops turning). i tried unplugging the 4pin ATX +12V power plug (correct me if im wrong but i think this the one that powers up the cpu) then tried to turn it on. it turns on, led lit up, cpu starts spinning and stays that way but of course nothing appears on the screen. no beeps.

could this mean that the cpu is dead? is it possible that a cpu could be dead after only a year? when i removed the cpu from the old mobo, i checked all the pins, all were complete and intact, no bends. it didn't show any sign of burns or any sign of possible frying.

oh, i forgot to tell you that when we tried the new mobo, it is on top of the cardboard box it came with so short circuits of any kind maybe impossible to cause this problem.

we desperately need your help guys... we wanna make sure if the cpu is really dead before purchasing a new one. thank you so much in advance....

good day to all!!

sounds like we really have to purchase a new one... damn... what could have possibly made the cpu dead? my friend had it only for a year and he doesn't use it that often...

it's warranty just expired last month, 2 weeks before the pc went loco... such bad luck ain't it... lol