If you do not hear the pump start up, it is NOT the rear bow latch - the latch is HYDRAULICALLY operated.

Your problem is to find out why the pump is not starting - the beep is to tell you that the TCM sees something that tells it not to start the pump items to start with, in descending order of likelihood:

Top open switch
Divider Switch
Loss of sync in the TCM (for this one, start engine, put top down and up three times, manually, including using a hex key to manually manipulate the latch - see my video for details)
Trunk fully closed switch
Trunk Electric Lock
Some sort of failure on the CAN bus