OK,
It happened to me once & never again (I hope)! There are several options you can do to address the cluster (after the fact).
1. You can buy your own brand new cluster (I did this online @ Duval Motorcar in Florida, MB dealer) for 700 some bucks.
2. You can have MB dealer order it for you for $1500.
3. You can have your old one reset by a cluster company in Springfield, Mass (BBA-reman) for about $250 for 2-3 days turnaround. I verified the model & sent photos, they said it can be fixed/reset. They specialized in Euro electronics and do japs too.
Installation by dealer is about $150
I drove the benz with my cluster not functioning for few months

, then my K40 crapped out. So I decided to do the first step and also replaced the K40 by dealer for total of $1500. It's easy process if you have time! I rarely have time anymore for that, that's why I ask my guys to help me with it

If you have time, I suggest do the 3rd option & install it back yourself. The battery minder is also good thing to have. I think the reason it happened is because one of the fail safe diodes blew (I think), that's why everyone recommends the battery minder. Anyway, that's my 2 cents worth. The car works great now
