When trying to restart from windows 10, the monitor goes into standby mode and the power light on the NUC is solid blue. The BIOS screen "Intel NUC" does not appear.
I need to pull the power out and plug it back in every time and then when I hit the power button, Windows 10 boots normally.
Shut down from windows 10 works fine.
Windows 10 Version 10.0.19041 Build 19041
BIOS Version/Date Intel Corp. FNCML357.0032.2019.1021.1624, 10/21/2019
I would start with BIOS update to version 0039. The BIOS update instructions you may read here. In your case the express method should work. Download the FNCML.0039.EBU.exe, double click on the .exe file and follow the instruction on screen. When asked to reboot, confirm it. Your NUC will reboot and the update will start and end automatically.
The express method did not work because of the computer refusing to reboot gracefully. I flashed the BIOS from a USB drive and now I have the latest firmware. Anyway, that did not help. I still have the same problem where rebooting is not working. Curiously enough though, if I run the "memory test" app from within windows 10, it is able to reboot just fine (and run the app). Not sure why regular reboot refuses to work.
On a related note, I did not find any similar issues being reported for the latest windows 10 "2004" update which got installed recently on my computer.
1. Next thing I would try is to reset CMOS: disconnect the Power Cord, open the bottom cover and disconnect the CMOS battery connector. Reconnect it and close the cover after waiting 15 minutes. Try now if the system restarts.
2. If it doesn't helps (assuming that before update to version 2004, the NUC restarted), I suggest you to repair your Windows installation with an in place upgrade.Using this method your Windows will be reinstalled, while all your data, programs and settings will be preserved.