vSphere ESXi Shell console terminated - ALT+F1 doesn't work ?

We have encountered interesting 'issue' recently. We couldn't login into ESXi Shell console no prompt to login even when ESXi Shell was enabled.

We press ALT+F1 and got:

Mistakenly, I thought that greyed timeouts mean that timeout is disabled but that's not true!

We checked the timeouts using ssh:

# esxcli system settings advanced list -o /UserVars/ESXiShellTimeOut

 
   Path: /UserVars/ESXiShellTimeOut
   Type: integer
   Int Value: 1
   Default Int Value: 0
   Min Value: 0
   Max Value: 86400
   String Value:
   Default String Value:
   Valid Characters:
   Description: Time before automatically disabling local and remote shell access (in seconds, 0 disables).  Takes effect after the services are restarted. 

The timeout value was incorrectly set to 1 what is 1 second - our ESXi Shell was enabled but timed out after one second :)

It seems that during customizing the ESXi host using e.g. PowerCLI the value '1' was set instead of '0' to disable timeouts.

So, why the timeout is greyed out? I found explanation in this VMware KB: 

http://kb.vmware.com/kb/2004746

Long story short this is ESXi Shell default behavior - timeout are grayed out as long as ESXi Shell is Enabled or SSH is enabled or both !

Disabling ESXi Shell and SSH - enable the timeouts modification:

the end.