XPS 13 9343 -- not booting up (likely mobo)

[techconsumer]

Of course it was 5 weeks out of warranty so I'm on my own there.

Wife's laptop showed power button lighting up but the screen stayed dark.

Force powered down, then held D then Power button and LCD test worked fine.

Ran diagnostic test (off > Fn + Power) and always get three beeps + three beeps + double trill sound, which repeats until I hit power again. Online references point to a motherboard issue.

Also did the various Dell PC Health tests (online) and some downloaded iolo tool that were useless (you have temp files that are slowing you down!) - everything passed.

Laptop booted up (no idea why) so ran F12 diagnostics - everything passed.

What's odd is this has happened twice now. After running the diagnostic test a few times, the laptop finally does power on as if nothing happened.

All files are backed up. What should I do next? Is there a better diagnostic test to run while it still works? Should I open it up and tighten all connections?

I'd rather not replace the mobo as it's $400 but that would be better than having a paperweight.

Thank you in advance!

Quick edit: Expanded on other diagnostics run

 

[Laptop_Nerd]

Hi,

Since every hardware test passed with your laptop, I would suggest doing a clean install of Windows 10 first and see if the same problem will happen or not.

Here's how to create a bootable Windows 10 USB or disc:
http/www.tomshardware.com/faq/id-2745957/create-windows-installation-usb-drive-dvd.html

And here's how to install Windows 10:
http/www.tomshardware.com/faq/id-2569562/install-windows.html

Hopefully this will help.

 

[techconsumer]

Thanks so much, Laptop_Nerd. Travelling but will try this when I get back.