If it is like the 124 it should have the bi-directional vacuum/pressure system for lock and unlock. Driven off the auxiliary pump that is either under the back seat or in the trunk.

The actuators have one yellow hose that has either vacuum or pressure on it. I cannot remember at the moment which mode (vacuum or pressure) causes which mode (locked or unlocked). I think all the actuator pods are all teed together from the same line for the doors, trunk, and fuel flap.

Unless you turned the key in the trunk lock to the "permanently locked" mode, you should be able to unlock the passenger compartment, freeing the trunk mechanism to the "unlocked mode" and that should allow you to push the button in to open the trunk.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech