/norestart prevents the computer from rebooting automatically after completion.
If you install .NET Framework using a repack, Microsoft Support will rightfully not assist you with any problems that arise. You will be entirely reliant on the repack's creator or the community forum where you found it for help. Official solutions, like the .NET Framework Repair Tool, may not function correctly on a system installed via a repack. microsoft net framework 481 offline installer repack