There's a thread on the FredMiranda.com forum that says a few users have experienced lockups of their 7D Mark II after upgrading to firmware 1.04.
From FredMiranda
I decided to update the firmware since I do have the 70-200II ( even though my 300 2.8 is usually on there )….Camera locked up twice shooting one game, I was looking through view finder turned away looked back through and had no info like it was shut off…the second time it was resuming from sleep….
One of our forum moderators recommends the following procedure after updating firmware. It can solve some issues, but not all.
My recommendation with any new firmware is to recordthe camera settings, and after installing the firmware, do a camera reset, remove the battery for a few minutes, then restart the camera and restore the settings. That will eliminate some issues, but not if there is actually a firmware issue.
Please report on our forum or the FM forum if you're experiencing lockups after updating to firmware 1.04 on your EOS 7D Mark II.
Read the thread at FredMiranda