console busy on SC for the domain on a Sun Fire 3800/4800/4810/6800

When you attempt to log into a domain on a Sun Fire 3800/4800/4810/6800 server and get the error

Connection refused, console busy          
the reason is that the console is still in use by another user, or the serial port session was not closed previously.


SOLUTION SUMMARY:
To fix this, telnet to the System Controller (SC) and log into the platform shell.

Example:

telnet HostNameofServer
Trying 129.148.xxx.xxx...
Connected to HostNameofServer.
Escape character is '^]'.


System Controller 'HostNameofServer':

    Type  0  for Platform Shell

    Type  1  for domain A console
    Type  2  for domain B console
    Type  3  for domain C console
    Type  4  for domain D console

    Input:          
Select 0 for the Platform Shell, then type: connections to show the active connections.

Example:

HostNameofServer-sc0:SC> connections        

ID  Hostname                 Idle Time Connected On   Connected To  
--- ------------------------ --------- -------------- --------------
  9 Localhost                00:01     Nov 01 19:58   Domain A      
 12 0.1.0.1          00:25     Nov 04 12:39   Console Menu  
  2 0.9.0.2          -         Nov 04 13:05   Platform                  
The Localhost is the serial port on the System Controller.

======================================================

console -d domain -f

OR

SC>disc Domain ID/Platform id