Alright, I tried again. With V5, V6, and V1 for good measure:
- I dropped the two files into the card's root directory
- I started the camera in play mode
- I selected "Firm Update..." from the menu
- I confirmed that I wanted to update "1.0.0.0 -> 1.0.1.1"
- The camera rebooted pretty much straight away
- A green LED between the view finder and the power button blinked three times. This is not anything special. It always does that when the camera boots.
- The was no blue LED, no blue splash and nothing new in the menus or on the OSD
- I am out of ideas :(
Each attempt to update the firmware creates a small binary file named "UpdateLog.txt". I don't know its format, so I cannot tell whether this has any information about why the upgrade failed.