LED flashes 3 times but won't boot up

[AbnormalyMe]

Computer will not power up.  The LED where the AC power plug is connected flashes 3 times (white), but does not power up.

[Echo_Lake]

@AbnormalyMe
Thank you for posting on the HP Support Community.

• Have you made any hardware/software changes?
• Did this happen after a recent window or software update?
• Have you tried any troubleshooting steps?

While you respond to that, let's try these steps: 

Firstly, run Hard Reset: Follow steps from the link: https://hp.care/2GnkMa8 (if the computer doesn't start up/power on you can skip the next step)

Next step, BIOS default: 

1. Turn off the computer and wait five seconds.
2. Press the Power button to start the computer and repeatedly press the F10 key to enter the BIOS setup menu.
3. On the BIOS Setup screen, press F9 to select and load the BIOS Setup Default settings.
4. Press F10 to Save and Exit.
5. Use the arrow keys to select Yes, then press Enter when asked Exit Saving Changes?
6. Follow the prompts to restart your computer.

Hope this helps! Keep me posted for further assistance.