After you enable the ESXi Shell in the direct console, you can use it from the main direct console screen or remotely through a serial port.
At the main direct console screen, press Alt-F1 to open a virtual console window to the host.
Provide credentials when prompted.
When you enter the password, characters are not displayed on the console.
Enter shell commands to perform management tasks.
To log out, enter exit in the shell.
To return to the direct console, press Alt-F2.
See the vSphere Installation and Setup documentation for information on serial port setup.