Motherboard seems to have power but wont power up

My friend has an Advent T9306 and the problem is that when i plug the PSU into the motherboard the light turns on for the power switch but does not go off until i switch the PSU off. when i press the power switch nothing happens. no fans spinning no hdd spin or anything. ive tried taking ram sticks out and still nothing. i was wondering if anyone could give me some help on what i could try to do. im not sure of the motherboard make or model but the processor is an intel pentium 4 HT. any help will be appreciated.
Thanks

The first thing I would check would be the mechanical switch. The power button has a cable that plugs into two pins on the motherboard. If you take something metal, like a screw driver, and briefly connect those two pins it should start the PSU.

If it doesn't, the next thing I would check would be the PSU itself. The fact that it's able to supply enough power to light up an LED on the motherboard doesn't really tell us that it isn't broken.

i will try that but i also have tried about 3 other PSUs which all do the same thing and just have the Light lit up on the power switch

Ok I have tried that and still nothing happens. If that's what I was doing what you said was right? The pins tht the cables for the power switch connect to?

Does your motherboard has any ATX_12v sockets such as this one? The motherboard could not be switching [completely] up because it does not have all the required power (I had this problem once). Just make sure that all ATX power sockets such as that one are connected to the power supply as well.

yes it does have that connection and it is connected to the motherboard and it seems the motherboard is getting some power as the power switch light is on