HP Spectre x360 14-ef2014nf will not power on

[Natoqc]

My Spectre x360 14 inch will not power on (purchased 3 months ago direct from HP).
Charger is fine, it works on my other Spectre, also swapped charger from my other Spectre. Same problem.

When I press the power button, the white LED turns on for about 5 seconds and then nothing.

From my browsing this seems to be a common issue. Most replies say to remove the battery but I can't and the product is under warranty. I was hoping to find a quick solution without going through the warranty procedure.

Have tried pressing power button for 30 seconds both with and without power cord. Also windows+V and power, still same problem.

[Natoqc]

Bit of an update.
After talking to HP they say to return the product under warranty, most likely for a motherboard replacement, but the Hard Drive will be wiped.
Obviously I do not want that, even though I have a back-up of my files, restoring everything to how I like it will take days.
HP said I could have a repair shop backup my drive.
I asked if I could open the computer and do it myself (I am quite competent and have already replaced many laptop drives) without voiding the warranty. The answer was yes so long as I did not break anything.
So I opened the computer thanks to the maintenance service guide that can be downloaded (thank you HP).
I unplugged the battery and thought I would give it a try powering up.
No luck so I plugged the battery back in. The battery charge light now turns on and the power LED stays on, it does not turn off after 5 seconds.

Finally after leaving it for about 10 minutes powered on the computer says CMOS checksum error. It then rebooted and now it works.