Why won't it power on .it just stays in standby mode .

Hold in power button for few seconds

Someone is going to have to go inside and check voltages and other things --no brand or model is indicated here so this is as much as I can suggest.

some design need audio signal in to get it wake up from standby mode.

CHECK IN BIOS MODE ,THIS PC NOT GOES TO STANDBY SO PROBLUM IN YOUR OS .FORMATE PC NOW CHECK .

There is a short in the power supply board, shorted regulator transistor, or diode, and capacitor, "sometimes a bulge at top" cheaper to replace than repair.

this is a problem with the switch mode power supply unit,check for the components not functioning in this unit and replace

Hello,

Your unit staying in standby mode is an indication that its having a power problem. Remove its plug from the wall and fix it back into the wall, then turn it on again. If its still stuck in safe mode, then the power supply board in the unit is the cause of the problem.

The power supply board might be defective and maybe that's why the unit won't power up. Its receiving power but it cannot transfer the current to the necessary part of the unit because a capacitor, diode, etc may have been faulty. Until these bad components are replaced, the unit might not come on.

To actually find out what's wrong, you need to disassemble the unit with a screw driver and check what's wrong. You will be needing a meter in order to test the components on the power board, once you detect any bad component, you can make necessary replacement at any electronics accessories store withing our vicinity. This is the only way by which you can detect the problem.

Of course, testing the power board with a meter will require someone that has the ability. So it you can't, then you might be needing the help of a repairman or you can call a friend that has the ability to help you out.

I wish you the best of luck.

Regards.....

So why do you need the computer in stand-by mode anyway? My computers are either on or off. Off saves power and hardware.

Completely remove the battery and unplug the power cord for a few minutes. Reinsert battery and power up. You can also hit F8 when starting and see if you can boot into safe mode.