Issue resolved. Both links provide the same solution to run net user in a Powershell script using the Run Command feature. Posting here the longhand version, for the record, from https://www.chrisjohnson.io/2018/02/15/domain-controller-in-azure-vm-with-expired-password/:
Solution:
Before you go and delete the VM and build up a new one I found an interesting way to fix this.
Updated 5/20/2021: The new way to run PowerShell via the admin portal makes things really simple.
- Go to the VM in the azure portal
- Click Run Command in the left hand navigation
- Choose “RunPowerShellScript” from the options
- Paste in the following PowerShell (obviously replace the username and password you want to set)
net user <YouAdminUserName> <YourNewPassword>
Then click Run and let the script run for a while and when it is complete your password will be reset correctly.
Can confirm this worked as intended to reset the Domain Admin password on an Azure VM Domain Controller with a lost Administrator password!