There are a number of issues that might be present, but the first fix to attempt:
CMD as Admin
cd ..
This changes your Directory to C:\Windows\
lodctr /r
If the previous step fails
cd WowSys64
lodctr /r
Then restart server. This should be all that is necessary.
Source Article: https://community.spiceworks.com/t/server-2016-stuck-in-reboot-needed-loop-after-updates/765706