Random Power On

In Windows Power Options, I have Sleep set to Never, Hybrid Sleep Off and Hibernate set to Never. Wake Timers is set to Enabled. Should this be disabled?

Like I mentioned, this happened from a shut down state.

I've not had this problem, but there is no bad effect to giving this a try.  It does not slow my boot up times to any noticeable degree on my system so I've left it this way as described below. 

As Cal has stated, Windows 10 by default does not immediately fully power off:

From:  https://www.howtogeek.com/243901/the-pros-and-cons-of-windows-10s-fast-startup-mode/

" Fast Startup combines elements of a cold shutdown and the hibernate feature. When you shut down your computer with Fast Startup enabled, Windows closes all applications and logs off all users, just as in a normal cold shutdown. At this point, Windows is in a state very similar to when it’s freshly booted up: No users have logged in and started programs, but the Windows kernel is loaded and the system session is running. Windows then alerts device drivers that support it to prepare for hibernation, saves the current system state to the hibernation file, and turns off the computer.

When you start the computer again, Windows does not have to reload the kernel, drivers, and system state individually. Instead, it just refreshes your RAM with the loaded image from the hibernation file and delivers you to the login screen. This technique can shave considerable time off your start up. "

Control Panel > Power Options > Choose what the power buttons do > Change Settings that are currently unavailable

Set the following:

"When I press the power button" -- Set to "Shut Down" in the dropdown box

"When I press the sleep button" -- Set to "Do Nothing" in the dropdown box

Remove the checkmark from the boxes:

 "Turn on fast startup (recommended)"

 "Sleep"

 "Hibernate"

Click "Save Changes"

Reboot and verify

Some systems don't do well with Fast Startup.  I don't know why these strange reboots are occurring, but on the off-chance that it is a USB Device, or a Network Adapter that is triggering a Wake Up you might try to disable both the "Allow the computer to turn off this device to save power" and "Allow this device to wake computer" bullets, through Device Manager for each device, under each's Power Management tab.  (Human Interface Devices, USB Controllers, and Network Adapters.)

The only device I allow to "Wake" the computer is the keyboard, and having USB controllers or devices turn off while in flight reeks havoc with a simulator.

But like I said, I don't have the same problem with the system booting up when supposedly "off."   Disabling Fast Startup should ensure the system expediently powers off and is not aberrantly left in a limbo state susceptible to being woke up.  

I suppose a faulty case button or its connections is possible and cheap to fix, or as Rob suggested a restore a good system image from a point prior to you noticing this boot up problem.  (I assume you have been making system image backups.)

Then there are the slightly more painful re-install options as Rob points out.

Best,

Don

I go one step further. I even turn off the power button on the power supply. But that's just me and probably doesn't make any difference so your mileage may vary.

I do not