Don't need to turn off instant go feature by regedit.
And reg may not work because some of the Tablet product have this settings in their BIOS...can't change the settings.
Once the system booted, turn off screen will force them going to sleep and ignore your settings.
But here, I put a cmd script for this situation... I think it will help and if it is, please mark it helpful/solved my problem.
https://github.com/Incubator85653/windows-display-void-output
You can download the script here but read the README first!
https://raw.githubusercontent.com/Incubator85653/windows-display-void-output/master/doSwitch.bat
DisplaySwitch.exe /external
timeout -t 5
TASKKILL /F /IM DisplaySwitch.exe
cmd
Be warn this be equal "Win + P" to second screen. Just like an old solution.
And you could try more "Win + P" to switch back main monitor.
BTW you should turn off any auto sleep in your powerplan while you're leaving your computer.
Yet a securely warn, this method require you not to lock your screen(Windows 10, Win+L).
So anyone who can touch your computer they can fully access your PC login account.
If it's not work or turn on monitor again in few seconds, use lower number in timeout
(timeout -t 3, etc)
The basic question is, in older system, such as Windows 8, you might be switch your screen to "second monitor" and keep it even it's not exist. Why someone wants do this? On mostly Tablet Device, TURN OFF monitor = sleep, that will make all working program
paused.(That damn Instant Go or what...)
Switch to non-exist second screen could turn off main monitor, and system will think screen still working. So you can leave your Tablet and let it keep do something you want.
Someone told me that could use "Win + P" turn off the main monitor to save battery. In older system, it won't check second monitor status so could be keep in non-exist monitor. But Windows 10 resolved (How ironic.) the problem so we cannot switch and keep
in non-exist monitor.(It will turn back main monitor after a few seconds automatically.)
My script use an idea that Kill Switcher 's task before it find second monitor does not exist. Unfortunately I spend 7 hours on this stupid things. Then it work , so enjoy it.
Can't turn off screen for long-time operating is a failed. What we need a Tablet? Low power consumption for long-time running is a good reason, right? Now thouse product can't turn off the monitor to save more battery.. funny.
Truly hope one day we don't need these extra to do what we want.