Something is dead as a doornail if it is completely dead or no longer working.
The phrase has been used in English for many centuries. A doornail was a metal nail fixed firmly into a door, making it lifeless and immovable.
The phrase has been used in English for many centuries. A doornail was a metal nail fixed firmly into a door, making it lifeless and immovable.
After the battery failed, the old phone was as dead as a doornail.