Turn signal went out on my wife's '06. So I changed it...no biggie. Next day she went to drive it and reported that the radio didn't turn on anymore. I checked it out...not only radio but NAV too. I was gonna do a hard reset. I texted my favorite Tech and he gave me a call...confirmed that since it's both radio and NAV it's likely MOST related and suggested that I do a hard reset. A couple things:

1. When I changed the flasher, I disconnected the negative battery terminal first. I just thought it'd be a good idea as a precaution. I think this is what did it. My Tech buddy mentioned that sometimes if the battery cable is removed the MOST system can throw a fit. It probably doesn't help that my Wife has a habit of leaving the radio on when she shuts off the Rover.
2. Here is the part I really wanted to share: my Tech buddy advised me that before connecting the pos and neg cables, but after disconnecting them from the batt, we should wait 15 minutes. This allows all the systems to go to sleep or otherwise discharge.

Anyway....did that and all was well. So lesson learned....and we can augment our description of how to do a Hard Reset.

I figured @bbyer would be particularly interested in this tidbit.

Cheers,
Houm

 

That is kind of the conclusion I also came to over the years; the 3 has to go to sleep before one disconnects the battery. As such, I get into the habit of opening the driver side window as just opening the door wakes the 3 up and the time thing starts over. As to 15 minutes, it sure takes more than a couple of minutes for my 3 to go to sleep.

Also I think I open the hood before I start the time as that is one reason for opening the drivers side window - to get at the bonnet release without opening the drivers door if you forget but I think opening the hood later might start the awake sleep process all over again.

 

Bbyer....I'm also stating that a 15 minute "nap time" after the cables are disconnected but before they are electrically linked, is advised.

 

I appreciate you clarifying that; I did not understand that part.
For me, that is not much of a problem as I am so slow, but I will add it to my Hard Reset instructions for the more agile.
The arrangement I have with Interstate is that I will disconnect and reconnect, but they have to lift out the old battery and drop in the replacement. Over the years, that H7 has got heavier.