I am trying to help my father in law with his 2002 SL500 (Silver Arrow). He hasn't been able to drive it for the past few months, and I went to start it up yesterday and found that the battery was dead. Since the battery is in the trunk, I tried to open the trunk but I could not. Is there a trick to getting the trunk open when the battery is dead?

I thought I just had to manually unlock the trunk, and push the button in, but no matter which way I turn the lock, the button does not open the trunk.

Thanks for any advice.