If you use the Control Window supplied with the latest Meridian config software (instead of Windows Hyperterminal), you receive unambiguous feedback (e.g. an "Entering maintenance mode" message or similar).

Select the "Command" tab. Enter the commands in the bottom left window and hit enter (or press the send button). If your connection is working, you will know.

Good luck!

Roon Developer and ex-moderator of this Forum
I am #25 in the HH1 photo of fame.