"RMA the board for a new one."
Apparently it was probably made in 2004.
It's extremely unlikely there's anything wrong with the power switch.
Sometimes a wire / the wires to the switch can get broken off at the switch when you've been fiddling with the case front - did you check for that?
Are you sure you have the correct wiring for the power switch connected to the right pins ?
Do you have the manual for the mboard ?
If you don't, it's available here:
System Panel connector page 41
It's a ten position header on the back corner of the mboard, two rows of 5 with a pin missing in one corner. The two pins in the row of 4 pins next to the missing pin are for the power switch.
Briefly shorting the two pins for the power switch does the same thing as briefly pressing the power switch.
If briefly shorting those pins doesn't boot the mboard, something else is wrong, or your mboard is damaged.
Examples of something else is wrong - a defective power supply, or a poor connection of the main connector from the power supply to the mboard power socket, can cause the "power good" signal to not be sent from the mboard to the power supply to turn it on fully, when the power switch is briefly pressed, or when the power switch pins are shorted briefly
"i switch on the computer from the wall and it turns on and i have to switch it off at the wall!! "
What do you mean by "it turns on" ?
Is the mboard working okay when "it turns on" ?
Are you getting video ?
Do you have a hard drive connected to it ?
If it does have one, is the computer loading an operating system from it ?
The mboard's bios has a setting regarding what it does after a power failure. If that's set to boot the computer rather than Stay off or similar, the mboard will boot when you plug in the power cable to it.
When you plug in the computer, or switch on a switch on a power bar that the cable is connected to, that can sometimes produce an electical "noise" pulse that causes the mboard to behave the same way as if the power switch were briefly pressed, and the mboard will boot. E.g. I have one power bar that has a switch that sometimes causes that, but only with one of the 3 computers connected to it.
Shutting off the mboard requires a software signal.
If you don't have an operating system loading on the computer, then you can't provide a software signal.
Pressing all three of the Alt-Ctrl-Del keys at the same time will usually reboot the computer, if you don't have an operating system loading on the computer.
Assuming the power switch is connected properly, holding it in for at least 4 seconds will usually shut off the mboard by the Soft off method, depending on a settings in the bios.
OR - shorting the pins on the mboard for the power switch for at least 4 seconds will usually shut off the mboard by the Soft off method, depending on a settings in the bios.