Acer 5520G Won't boot up, I'VE TRIED EVERYTHING

Hello there, I have an Acer 5520G laptop that died just over a month ago, the problem is when I press the power button the power lights come on, the hard drive turns on and the fans kick in but 1 second after I hit the button it immediately turns off, then comes back on again, then turns off, then goes on again, again and again till I do a battery pull. I've tried with a different battery and charger same problem, I've had it to bits, ram out, HDD out, keyboard out, I've tried EVERY SINGLE thing I can, but still the same problem.
I heard that this is a major fault with these laptops and people have found success by holding the power button down, but that doesn't work either. So PLEASE if you have any advice and wisdom to help me fix my laptop, please reply. I need this laptop urgently for school and I can't afford £140 for a repair.

P.S. I'm not squeamish with technology so I'll happily do WHAT EVER IT TAKES to get this fixed, except for pay money etc.