blackhawkimpact

So recently I took my 99 ml320 to the store and when I came back it wouldnt start. It does not start or crank. When I turn the key all the lights come on and then it clicks onceand everything shuts off. When I do it again nothing turns on, no lights, no click unless I unplug the battery. I already tested the battery and its fine.
What could it be? I been searching around and found only one thread somewhat similar to mine and said that it might be the key??? I dont have an extra key so I dont what to just go buy a key. Thanks for your help.

art_arev

It could be your battery. It could be ground terminal. Have the battery checked by a pro.