Restart your server by issuing the command restart. Stay online while this process takes place.
When the Starting Windows window shows up, press the Esc key and 8 to give you Advanced boot options.
Advanced Options Boot
Choose Last Known Good Configuration (your more recent settings that worked) and hit Enter.
You will see EVENT: The CMD command is now available. Extensive options are provided by the command prompt ("DOS prompt") that can be started and used with SAC. A new command channel must first be created. Several threads (e.g. the SAC and a command prompt) are managed in "channels". Channel 0 is always used by the SAC itself.
CMD Command is available
Enter cmd to create a command-prompt channel.
Command Prompt Session successfully launched
The ch command displays a list of the channels currently being used. In addition to the channel number, "(AV)" indicates that the channel is active and available via a virtual terminal (V = Virtual Terminal). The channels can also be uniquely identified by name, e.g. Cmd0001.
There are two ways of switching to a channel.
From SAC using the ch, or pressing <Esc><Tab> in sequence. A description of the channel appears.
Press any key to switch to the selected channel and log into the server.
Using the backspace key will delete the characters on the screen but the Serial Console will not recognise the deletion of already typed characters. If you make a mistake while entering your login credentials, authentication will fail and the channel will be closed. You will then have to create another command-prompt channel.
Enter Login Credentials
If authentication succeeds you will see the usual command prompt. Enter commands here to stop or start services, modify files and disable filter rules, to only name a few.
Authentication was successful
For additional information, you may want to reference: