HP laptop shut down unexpectedly

HP Pavilion 15 randomly shuts down incorrectly if fast startup enabled

I've just updated an HP Pavilion 15 from Windows 8.1 to Windows 10 [Home 64 bit]. If fast startup is enabled, the laptop freezes at the very least step of the shutting down process. The shutting down process goes like this:

1. First you click on shut down
2. The shut down screen appears
3. The screen turns off and then the fan starts to spin at high speed
4. After 4-5 seconds, the fan stops
5. The laptop is completely turned off, no lights are turned on [in most of PC's]

Well, my problem is that randomly, the Pavilion 15 freezes after step 4 has been completed, with the light of the ON/OFF button turned on forever. Sometimes it turns off correctly, but many other times this happens. If I disable the fast startup, this won't happen and it will always turn off correctly.

What can I do?
How is it that it's random?

I've tested this with no apps running on background, so that can't be the reason, besides, no apps or programs can freeze the system after the step 4 has been completed, since they are all shut down after step 1.

Also, the fast startup option was activated when I was using Windows 8.1 and never had a single problem with this laptop.