I had this problem too losthill
I meet an error when I test the Sense Hat," it cannot detect the RPI-sense FB device" as attached picture. How can I solve this problem ? .
It was solved by doing the following:
The R Pi is not recognising the Sense HAT. So go into the Terminal and alter config.txt
with the instructions below:
sudo leafpad /boot/config.txt
Scroll down to the bottom of the config file and type:
dtoverlay = rpi-sense
then 'Save' the config file and reboot your Pi.
Hope it works.