NakaML

Today when I started ML "Very low fuel" warning message came on and diesel gauge was all the way on the bottom even though I had half a tank. Same time headlights started to blink and will not stop (engine on or off with keys out, car locked). No "check engine" or other warnings were on, just blinking headlights and "very low fuel" message. I added some diesel, now warning message is gone, fuel gauge showing close to full tank, but headlights are still blinking. Tried: retightening fuel tank cap, adblue cap, leaving key in position 2 for 30 secs, position 3 for 30 secs etc. When i start the engine I hear 4-5 beeps, headlights keep blinking. Has anyone had a similar thing happening with their ML320 Bluetec?