I followed the instructions on this page.
I was using ArduPlane4.0.1 rather than the ArduCopter 4.0.0-dev when I flashed the bootloader. (As you can see in the screenshot below.)
I updated the bootloader, no issues, waited for sold green lights, rebooted (for sure had solid green lights + waited another 30 seconds before rebooting), reconnected. But now when I click on SLCan Mode CAN 1 on Mission Planner nothing happens, no errors, I can’t finish updating the firmware. Sold green lights still. I took a screenshot of the UAVCAN firmware details right before I flashed the bootloader.
I’ve tried swapping to the ArduCopter 4.0.0-dev but still no luck. Any ideas?