Issue: You are performing an Sharepoint upgrade (via PSConfig.exe as mentioned here for example) but got the error Message "Cannot open SPTimerV4 service on computer '.'." as seen below:
An error has occurred while validating the configuration settings. An exception of type System.InvalidOperationException was thrown. Additional exception information: Cannot open SPTimerV4 service on computer '.'.
Solution: Make sure you are running the Powershell with "Run as Administrator" even if the account you are using has local Admin rights.