I cannot access my battery how can I jump start the car

Ok

Actually there is a power block under the front of the foot space passenger side pul back carpet and remove plate held by 4 screws.

I have the same problem, never had a boot lid key, always meant to replace -I have now! What I did was strip the thick red wire under the right fusebox under bonnet and connect battery charger to it. Worked well enough. when it had enough charge electric boot release worked. Then carried on charging in boot

Thank you for the demonstration. After having AAA decline to help me but instead suggest that they would be willing to tow my car to a Merc dealership, and after several failed attempts to find a locksmith willing to help, I went online, found your post, followed your directions, and was able to open my trunk and charge my Merc. Thank you, thank you, thank you!