Morning Donald

We are a BMW Forum but having personally owned and run 3 AMG Mercedes under the Bonnet (Hood) on the left of the car (Drivers side for you) Mercedes put a plastic capped Pos terminal the Neg terminal was on the suspension mount. Same arrangement on a friends 2004 230 CLK

If you got burning it could be one of your connections was in the wrong place or just dirty. Hope it didn't melt anything

Dave

Hi Donny. There should be a red + under the hood. On the wheelarch side fender will be a large nut. This is the - where the black lead goes. 
then use a charger so another battery to put power into the car and open the boot/tailgate that way. 

I tried hooking up my charger but got just a pop! The charger didn't make the pop, so I guess something in the car made the pop. I tested several fuses, for a blow out but saw nothing.  I will put in a new battery for the fob. If that doesn't work, I will look for the red battery cable under the rear seat and cut the wire; hook it to a good battery and see if that will work. 

To top that, I was looking for a tool to pull fuses and opened up the fuse cover in my '92 BMW E36 five-speed; and found out why I had been smelling burning plastic for a couple of weeks. The car was running just fine but found out that I had a small fire in the fuse box. The heater fan motor must have locked up. UGLEY! Something more to work on.

Re: dead battery keeps trunk or boot from opening. OK. I stumbled upon (in my brain), that you have to push the black surround keyway about a half an inch in, while the emergency key goes in. Amazing! Too bad it won't work for a 2011 BMW. re: 2003 Mercedes CLK430.

Now I just have to put in a good battery and figure what, and where, went POP.