This is a repost of a message I left on fujicamerasaus instagram post:
"I've had an issue with this update, the camera powers on but all controls are unresponsive after the update is applied. This occurs when a memory card is inserted in Slot 1, but everything works fine with a single card inserted in Slot 2. The memory cards I use are both Lexar Professional 128GB UHS-II SDHC. Users who take advantage of the high speed shooting capabilities of this camera should be aware of this before updating, as the camera will still work, but Card Slot 2 is not UHS-II spec AFAIK."
Might want to hold off on the update until this is checked out.
[Edit] Well I'm not quite sure what I did, but I managed to get everything up and running again. I initially tried reformatting both cards in Slot 2, but this didn't fix the issue by itself. I then tried to update the firmware of my XF 55-200 lens, but the camera can only read firmware files from Slot 1. Having then changed slots and powered the camera back on I was greeted with a blank screen, and again I had to pull the battery from the camera (about the 20th time so far). Leaving the battery out for an extended amount of time, and blowing in the card slot and on the card contacts, I tried again, and both successfully updated the firmware on both lenses, but the camera is now back up and running with cards in both slots. Not the smoothest process I've been through, but glad to have it resolved in the end.