Starting issue

[lorenzorollininthebenzo]

Hello so my beloved clk320 has "randomly" stopped starting.
I turn the key to accessory I get a loud click, I go to turn the engine on I get an even louder click and the dash turns off and I have to remove the key to be able to do anything again Checked the starter relay it's okay but there is a spot where a plug looks like it should be with a little prong beside the starter relay but it's empty anyone know if there should be something plugged in there I think it's labeled G

 

[DREAMER NO2]

Flat battery check it with a meter ..

 

[lorenzorollininthebenzo]

Nope had it connected to a battery charger

 

[lorenzorollininthebenzo]

It works fine until I turn the key I can play my subs in the car and all she just won't turn over

 

[DREAMER NO2]

Get a meter on it radio will work on very little power

 

[mioba]

Charger means nothing if the battery is dead (beyond being a battery holding charge) proof is in the pudding - VM all the way.