Dell Desktop won't turn on

If you're using a power strip, surge protector or uninterruptable power supply, disconnect those and connect PC directly to a known working outlet.

You can also try this:

Power PC off and disconnect power cord from *rear of PC*. Press/hold power button for ~30 sec. Reconnect power cord to rear of PC and see if it boots now with only mouse, monitor and keyboard connected. If that doesn't help, try using a different power cord. You may be able to swap the power cord from the monitor or a printer with the one from the PC, at least to test the cord.

With the PC unplugged, press/hold power button for ~15 sec. Open the case just enough so you can see the motherboard inside. Then carefully plug the PC into the wall. Do you see an LED light up on the motherboard, without pushing the power button? That LED should be on 24/7 as long as the PC is connected to a working outlet, even if the PC isn't turned on.  If no LED, either the motherboard isn't getting power, eg possibly a failed power supply, or maybe the motherboard has failed.

Hello Ron,

Thank you for your suggestions. I will try the things you have suggested when I go over to my friend's house again sometime today. I'll let you know how it goes.

Thanks again,

Victor

Dimension 4550 is very very old.  An Optiplex GX620 would be able to recover any data and run the software on the current unit.

Getting a GX620 TOWER also ensures that you will be able to replace power supplies well into the future as well as upgrade to windows 10 in 2020.

https://www.walmart.com/ip/404045744

Hello Ron,

I've tried the things suggested, and there are no lights and the computer won't boot. Too bad, I'm guessing the power supply got damaged during a power failure even though it was plugged into a surge protector. Bummer.

Thank you for your assistance!

Sincerely,

Victor

Hello Ron, I've tried the things suggested, and there are no lights and the computer won't boot. Too bad, I'm guessing the power supply got damaged during a power failure even though it was plugged into a surge protector. Bummer. Thank you for your assistance! Sincerely, Victor

Not even the LED on the motherboard? That means it could be either power supply or motherboard.

Try clearing BIOS. After you unplug, press/hold power button for ~15 sec, open case and remove motherboard battery. Press/hold power button for ~30 sec. Then reinstall the battery, close up and see if it will boot with only mouse, monitor and keyboard connected.

You can also try the paperclip power supply test. Power off and unplug. Press/hold power button for ~15 sec. Open case and disconnect main power supply connector from the motherboard. Insert the ends of a bent paperclip into the connector to "jump"  the green wire to a black wire. (Don't cut or remove any wires from the connector.)

Now plug the PC into a working outlet. See if the power supply fan, other fans, and hard drive spin up. If they don't, then the PSU failed. If they spin, that suggests the motherboard.

Either way, contact the manufacturer of the surge to see if they offer a protection warranty for damage to the PC. And also contact the local power company. Some of them have insurance to cover damage/loss from a surge or outage.

Power failures do not damage electronics.  That is a conclusion only from observation.  

Power failure can be created by something that also causes damage.   That is conclusion based in how hardware works.

A paper clip test can report a PSU defective.  But it cannot report a PSU as good.  Normally a PSU provides massive protection from something that can damage appliances and can cause a blackout.  But something adjacent to that computer would have compromised (bypassed) that protection.  Therefore damage could be due to a transient connected directly into the motherboard by that protector.

A simple procedure can identify what is defective long before even replacing one part.  Unfortunately others want you to shotgun - keep replacing good parts until something works.

A best procedure using two minutes of labor can identify what is defective.  Something completely different should be installed so that a computer and all other appliances (furnace, dimmer switches, dishwasher, vacuum cleaner, clocks, refrigerator, LED & CFL bulbs, central air ... everything) is protected.