Dead inkyphat?

I have a 2018 era inkyphat installed on a pi zero and which has been working fine since it was installed (updating once an hour).It now seems to have died, in that the code runs without error, but the screen does not update. (Tried and others, same result).

pi@inky:~ $ sudo pip show inkyphat
Name: inkyphat
Version: 0.1.1
Summary: Inky pHAT Driver
Author: Philip Howard
License: MIT
Location: /usr/local/lib/python2.7/dist-packages
Requires: spidev, numpy, RPi.GPIO, pillow

Any idea how to determine if it is really dead or just resting?