Hello! I tried to start my 1985 300D one morning and at first it started to crank OK, I waited for the glow plug light to shut off then turned the key. I thought the engine turned over and let go of the key but it didn't start.
I tried to start it up again, and everything electrical shut off. Turning the key did nothing to the car, no lights on in the dash . . . nothing. I checked the battery and it was OK.

Next morning, I tried to start it up and there was lots of clicking going on behind the dash and the panel lights were fluttering on and off. It was chaos behind the dash, and there was no starter activity. The glow plug lights didn't light either.

If anyone out there could provide me with a starting point, I'd greatly appreciate it, and would like to join the happy MBZ owners out there. I don't know much about cars and especially diesels. I just purchased the car the day before with 162K on it and then this all happened literally the day after,

Thanks!

Check the cables to the battery, remove any corrosion and make sure they are
snug/tight

Problem solved. It was the battery terminal connex.

Thanks Gauge!