This happened to someone I worked with years ago. Not in a cubicle, but in a locked basement office. I was his supervisor.
He died in the office on a Friday evening. He had taken off work the following Monday and Tuesday because he was going to do some work on his house.
His brother was supposed to meet him on the Saturday, but he never showed up. By Wednesday, the police were involved, and they called me to ask me to see if he was in the office.
I worked in a different building a few blocks away, so I headed over.
I didn’t have a key to get in his office, but there happened to be a ladder, so I climbed up and popped out the ceiling tiles to look over the wall.