Ml270 won't start

[DOMNAT]

Hi , started my 51 plate ml270 this morning no problem and left it running while i de iced the car and warmed it up.
This took about 15 minutes - turned the car off to go and lock up the house.
Returned to the car to start up and nothing!!
When i say nothing the radio came on the fans came on and the initial warning light clusters came on but the car would not turn over - simply click.
I tried to jump start the car using my wifes rav4 but the same scenario.
Any thougts?
Thanks

 

[JOB-BLACK-RAT]

Hello and welcome to the forum, please let me bump your question to the top of the list again

Any thoughts folks to help out our new member

 

[donohoeIRL]

I would say with all the electronics running for such a short period it wouldn't have given the alternator enough time to replenish the battery, and with such cold weather it would take such a toll on the battery too. Try putting the NEG lead on the block instead of the battery.