The body of Adrian Matthews was found in a small space at a converted property he was renting in Otham, Maidstone, but it is unclear why he was there.
Coroner Patricia Harding heard how a mobile phone was pressed against his chest, but he was unable to uncross his arms and reach it.
The inquest was heard at the Archbishop's Palace in Maidstone
There was also evidence to suggest Mr Matthews had tried to escape from the cavity in Highwoods Farm, in Holly Farm Road.
DS Neil Kimber, from Kent Police, said: "I can only imagine (he made) a frenzied attempt to extricate himself from the hole."
Mrs Harding asked if it was possible the cleaner was surveying the hole to install an electric system to help cultivate several cannabis plants growing in the room next door.
But DS Kimber said there was no explanation that would give "absolute clarity" into what happened.
"I can only imagine (he made) a frenzied attempt to extricate himself from the hole..." - DS Neil Kimber, from Kent Police
Mr Matthews was last seen at about 1.30am on Tuesday, August 27, when he left the home of his friend, Joe Sage.
He read a text message at 6.35am, but his mobile showed missed calls and unread messages from later in the afternoon.
His body was found by Mr Sage's father Alan, who owns the farm, two days later.
In a statement, Alan Sage said his son had asked him to check on Mr Matthews because he could not get hold of him.
The site owner discovered a hole cut out in the floor that had not been there before Mr Matthews moved in about four weeks earlier.
This was where the tenant's body was discovered.
Another hole had a ladder that led to the cannabis plants on the lower floor.
Kent Fire and Rescue Service removed the wall so paramedics and police could examine the dead man.
They found a piece of plywood lodged beneath Mr Matthew's rib cage.
Mrs Harding gave the cause of death as compression of the chest and recorded an open conclusion.
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