Inspiron 620 doesn't turn on--- very disappointed with Dell

Sounds more like a power supply problem to me than motherboard.

What color is the power button and is it steady or blinking when it won't boot?

If you mean the green LED light in the back of the tower... the light is green and steady

Thanks

I meant the LED inside the power button on the FRONT of the tower.

The white LED inside the power bottom is constantly white.

The white LED small lamp below the power bottom is blinking... it is off in the attached picture 

Thanks

The blinking LED below the power button is probably the hard drive activity light which should go on/off when the hard drive is being accessed.

Does the power button turn solid white even when PC won't start? Or, when you press it but PC doesn't start, is the power button LED off or on?

When was last time you replaced the motherboard battery?

When the pc doesn't start the power LED is OFF... it's even blink
I never replaced the motherboard battery 

for the past few days, before going to sleep i turn off the power supply so I can turn on my pc in the morning. This trick seems to work and i had no problems for the past few days turning on my pc but i don't know why this is happening !!

Any clue

Thank you for you patience!

That sounds like a failing power supply. The only sure way to know if it's the power supply is to have a professional test it or to install a known working power supply.

If you can live with shutting off power at the mains, that might be the thing to do but the power supply may eventually fail completely and your trick wiil stop working.

Also, if you're shutting off at the mains, you're relying on the motherboard battery to hold the BIOS settings when there's no power to the system. If the battery is weak or dies, the PC might not boot even if the power supply is still working.

If you click Support at the top of any forum page and follow the links, you'll find the service manual for your system with instructions to replace the motherboard battery (and power supply too). It's a CR2032 3-volt lithium ion coin cell battery, ~$2 at discount stores. If you can't do it yourself, maybe you have a geeky friend who can help.

Before you change the battery, reboot and press F2, before Windows starts to load, to open BIOS Setup. Copy down all the current settings. When you remove the motherboard battery, BIOS will revert to factory default settings which might not be correct for your specific configuration. So after you replace the battery, you'll want to go back into BIOS Setup and make sure all the settings match what you wrote down. Be sure to save any changes before exiting setup. The system will reboot automatically from there.

And while you're in BIOS Setup, look for Power options. You'll probably find one that tells the PC what to do when recovering from a "power failure" (eg, you turn the power back on at the mains).  If you set that to Reboot, the system will boot itself as soon as you turn on the power in the morning and you won't have to press the power button on front of the tower.

Post back if you have any more questions...

One more thing...

After replacing the battery with a new one, try leaving the mains on overnight and reboot by pressing the power button.

There's a (small) chance the new battery will fix the problem, and you might not need a new power supply, but I make no promises... :emotion-5:

I'm very thankful for your informative reply!
I really appreciate it

I will try changing the motherboard battery and see, then if it didn't work I will change the power supply.

Regards
Chris