Register Managed Account: Access Denied - SharePoint 2010

To Register a Managed account, went to: Central Administration >> Security >> Configure Managed Account >> Register Managed Account

Central admin returned the error: An error occurred while getting information about the user at server : Access is denied

To solve this issue, you need to add the account using PowerShell:
Log onto you server using an account from your internal domain (you need to do this so it can retrieve the info it needs from this domain)

Execute the below commands in PowerShell:

$credentials = Get-Credential

Now in the login prompt, enter the managed account details

Now, Enter:
New-SPManagedAccount –Credential $credentials

That's it . Now the new Managed account has been added