shorted mobo ?

Most likely the light on the mobo shows that the 5 volts standby voltage is applied to the mobo. This is ALWAYS the case as long as the power supply is plugged into a live 120 VAC outlet, and the switch on it's rear is on.

If you are in the habit of fully turning the supply off [which removes the 5 volt standby voltage, and disables the power mgt logic], it is possible that the first turn on try after repowering the PS will simply glitch on and then right off again.

If you want to turn the power supply off each time, you can go into the BIOS and enable restart after power loss. If you do that the system will start up without even having to hit the front power switch.

Generally don't assume/guess a specific failure, do some troubleshooting which I assume is why you posted here.

any switch please say whether it is being flipped from on to off or from off to on.

Get over the being angry and troubleshoot slowly and logically.

For example the 5 volt standby light not coming on is more likely a power supply failure.

I can tell you how to test the supply with the power connector removed from the mobo. [also unplug the 4 pin 12 volts and all drives or molex connectors.

If you want to know how, let us know if the PS to mobo main connector is 20 pin or 24 pin. If there is a Green wire in the connector that is the wire of interest.