2007 Lucerne CXL. and 1995 Lesabre currently, past 1973 Riviera, 1968 Riviera
From what you've posted the trunk mechanism is not disengaging and may need replacement. The only way to open the trunk is to go through the backseat pass through and pull on the emergency release on the trunk mechanism. Long shot may be to push up on the trunk lid while clicking the opener, but it's under the wishful thinking repair.
Mine started acting up but opened with a side of the hand bump near the bottom of the deck lid. Lubed the actuator and is working fine, but I tied a small cloths line rope to the emergency release and fed it up to the rear seat opening just in case.