(as) dead as a doornail
US /əz dɛd əz ə ˈdɔrˌneɪl/
UK /əz dɛd əz ə ˈdɔrˌneɪl/
1.
completely dead; no longer alive or functioning
:
•
The old car was as dead as a doornail after the accident.
•
I tried to revive the computer, but it was as dead as a doornail.