My Dell desktop Series 500 doesn't turn on...

Brink said:

It does sound like the PSU may have bitten the dust, but it may be best to have the computer checked by a tech to verify.

Yes, that would be the first place I would start...

Brink said:

It does sound like the PSU may have bitten the dust, but it may be best to have the computer checked by a tech to verify.

I think you're right, but...is the PSU something built-in the computer?

Compumind said:

One more thing and it's a real long shot...

Does the computer have a cover removal tampering mechanism (interlock) built-in?
This needs to be turned off, if it does. FWIW.

Oh thank you but I don't think I have it. I guess I would know it if I had it? Thanks again!

Adela said:

I think you're right, but...is the PSU something built-in the computer?

It is mounted inside the case, usually in the rear and at the top or bottom. The main power cord plugs into the PSU..

My PC suddenly fails to boot when the CMOS battery voltage drops - see Strange Boot Failure - Why?

I recommend replacing the CMOS battery - load the BIOS defaults after you do this.

Is there an LED indicator light on the motherboard which should be on if there is standby power being supplied to the motherboard?

THANK YOU ALL so much for your great help! I know it's getting much too complicated for me even to just read the complications without having attempted to actually do something within the computer, lol! However, God knows I've been trying and trying things suggested without luck.

Yes, it is an old computer but it's a very good quality as it lasted a lot more than other brands and only now it happened something maybe unsolvable, or at least I feel so. Hence I had thought if it's something I can do - with you kind people's help - then I'll save it to use when my new laptop fails and I need to reach help for the new one.

There's a Microsoft Store not far from me where they'll do a diagnostic and may even put it up to date without charge if it doesn't need to replace a part. Very fair deal; however it's not easy for me (an old lady) to carry it around even from my floor to a taxi, but I may just do that when I figure out how. :)

Again A BIG HUG AND THANK YOU to all of you wonderful people!!! Adela