The "smc -stop" command to stop the Symantec Endpoint Protection (SEP) service does not work from a CMD window. The command works fine from Windows Start menu - Run.
In the CMD prompt the following message is shown:
'smc' is not recognized as an internal or external command,
operable program or batch file.
The smc.exe file is not in the environment path used by CMD, but is in the Windows registry "App Paths" key used with Start - Run.
Instead of "smc -stop" and "smc -start", use the commands "start smc -stop" and "start smc -start".
The "start" command in a CMD prompt will use the Windows registry "App Paths" key, and find the smc executable.