Hello, quick video on how to troubleshoot the HP All-In-One Desktop computer when it won’t turn on and it is beeping.
A lot of HP forums recommended people buy new AC adapters because they may not have enough power to start the desktop. This still might be your problem, but TRY TO REMOVE THE WIRELESS USBs FIRST.
After a scheduled update, my computer would not turn on and the screen was completely black. It beeped 3 long beeps and 4 short beeps.
First, unplug all the cables from your desktop including any wireless devices like the keyboard and mouse. This is critical. There should be nothing connected.
Then press the power button for 15 seconds while it is unconnected.
Then Plug in the AC adapter cable into the desktop again. This should be the only cable connected to your computer. Then press the power button again while it is connected.
The computer will begin to beep again. 3 long beeps and 4 short beeps. They are really loud and annoying but WAIT for the beeps to cycle through 5 times. Almost immediately after the firth cycle of beeps the error screen will show up for a couple seconds and disappear very quickly.
It should show a keyboard error.
If it shows an Unsupported Adaptor Error, check again if you removed the wireless USBs. Removing the Wireless USBs is Critical.
After the keyboard error, it’ll show a blue alert that the CMOS checksum is invalid. Since the wireless devices are not connected, touch the enter key on the screen to restart the computer. It should be touch screen compatible. Wait a little while for it to restart. If it does not restart on its own, just press the power button again. It should show the HP logo powering on and a percentage.
Then just enter your pin with the touch screen and wait for the system to come back. Plug in your keyboard and mouse again and reconnect to the internet. After that, you should be good to go.
Hope this helps someone! Please let me know if it did! :))
Cheers!
NOTE: I am not a professional but this is what worked for me.