After changing ESXi local user password expiration policy with the Security.PasswordMaxDays option, ESXi could become inaccessible from Shell or SSH with local user (such as root).
Reference: Configure the Passwords and Account Lockout Policy in theVMware Host Client
By default passwords would never expire.
The local user password becomes expired after changing policy and unable to access from SSH and Shell.
Log in ESXi at DCUI and change local user password accordingly.
ESXi should be accessible from SSH or Shell now.