flashing red and green lights
 

My E230 1997 model has been running quite smoothly since I bought it and has done 45,000 miles. Recently I started the car in the parking and after a few minutes of running it stopped. Tried to restart without any success. The red and green lights are flashing alternatingly. I thought the battery is dead or the remote batteries are dead but no.. I recently spied that the radiator is wet and recalled that some 4 weeks ago, the radiator poured all the water but after I refilled, everything was normalised then. I also recall that during that time, there was a hissing sound coming out of the bonnet. I did not drive the car without water for more than 500m.
Is there anybody there who can assist or give an advise. I am desperate and I have not driven the car for 3 weeks.