Here is the sentence:
Closing the hotel room door and pulling the heavy suitcase to the elevator,
the relaxing beach vacation came to an end.
Nice move! You recognized that the modifier is dangling. Closing the hotel room door and pulling the heavy suitcase to the elevator, a participle phrase, has no target in the sentence to describe.
To fix the problem, you should revise the sentence like this: Closing the hotel room door and pulling the heavy suitcase to the elevator, Monica realized that the relaxing beach vacation had come to an end. Adding Monica to the sentence lets the reader know whose happiness has ended.