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 ? .
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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.
Anne