*Update* All-in-one shut down unexpectedly and won't power up. No green light.

[archaeor]

All-In-One 24 shut down unexpectedly on its own yesterday. Turned it back on and it powered up normally. Today it shut down again, but won't power up. No green light on back above power cord receptacle. Tried a hard reset (unplugged power cord and held On button for 15 seconds) and also tested AC adapter/power cord with a multimeter and got 19.5 volts at the computer end. Any ideas? Thanks.......

*Update* Last night before bed I tried one last time to turn it on and it started up normally.  This morning while online, it crashed again and won't power up, just like yesterday. Motherboard or power supply problem? I'm stumped......

[WAWood]

@archaeor 

My guess --it's overheating -- because it shuts down after it has been on for a while and when you leave if off to cool down, then it powers on OK -- but then shuts down again after it gets warm.

Software failures will generate on-screen messages, usually about not finding an Operating System or not being able to boot. When the screen is blank, the PC is experiencing a major hardware failure.
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To determine the cause with hardware failures, you have to be able run diagnostics. We have no way of accessing your PC from here, so we can not do that for you. You have to do it yourself.

You do this by pressing the Esc key repeatedly when rebooting and then, when the HP Startup Menu appears, selecting Diagnostics (usually F2) and letting it run.

If it is NOT possible to run diagnostics, or if that does not work, then there is NOTHING more you can do by yourself -- and there is NOTHING we can do because we have no way of accessing your PC from here to run diagnostics or repair hardware.

You will need to have the PC physically examined in a service facility by folks that can run their own diagnostics to determine what is wrong with it.

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If your PC is still under the original one-year HP warranty, or if you have purchased an extended warranty from HP and this is still valid, then having HP do this is an inexpensive option for you. In that case, you should contact HP Customer Support to see about having it repaired or replaced under warranty.

To contact HP Support see the following link to create yourself a case number:

Step 1. Here is the link: https://support.hp.com/us-en/contact-hp
Step 2. Enter Product number or select to auto detect
Step 3. Scroll down to "Still need help? Complete the form to select your contact options"
Step 4. Scroll down and click on: HP contact options

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If your PC is no longer under warranty, then it will cost you up front to have HP examine your PC. If you want to do that, you will have to contact an HP Repair or Service Center to see if they can examine the PC to determine the cause(s) of the problems, if it can be repaired, and an estimate of the repair costs.

Since you live in the U.S., here is a link to the HP Service Repair Centers:
https://www.service-center-locator.com/hp-hewlett-packard/hp-hewlett-packard-service-center.htm

If that link does not provide the results you want then use the main HP link:
https://support.hp.com/us-en/contact-hp?openCLC=true

Good Luck

[itsmyname]

@WAWood -- very good & thorough reply.

To the author: did you purchase the HP Care Pack, to add more months/years onto the original warranty?

[archaeor]

Thanks WAWood for the reply.  If it's overheating, would I be able to feel the heat through the case? I've felt the exterior each time it shut down and didn't feel any excess heat. Also, why would it take 8 hours or more to cool down if it was overheating? It sounds silly, but what if I put the computer on the air-conditioning vent for an hour or so and see what happens? If it ever fires up again, I'll run the HP hardware diagnostics.  Thank again!

[archaeor]

Itsmyname...... Nope, no HP Care Pack.  I've been using HP products for over 20 years and never had a problem. This computer is 18 months old.  Thanks for your reply.....

[itsmyname]

@archaeor -- as soon as you can after booting Windows, download, install, and run the free SPECCY software. It will display the temperatures (motherboard, CPU, fans, disk-drives). Then, "refresh" the SPECCY screen every 10 minutes, to watch for changes in temperature. 

In addition to checking the temperature of the case, check the temperature of the air exhausting from the fan inside the power-supply.

With an intermittent "open-circuit", it can take quite a while for room-temperature air to go through the PC (given that the PC's fans are not running), to cool-down the motherboard to close the circuit, as it "flexes" back to a "working" connection.

[archaeor · Accepted solution]

Problem Solved: Turns out I needed a new power adapter.......