Since updating to 3.5.x sometimes I get the Error IMU Start failed Check BRD type.
Setup the brd_type from auto (0) to Pixhawk (2) does not help.
Never had such issues with AC 3.4.x or before.
In the meantime I updated the bootloader but this also makes no difference.
Any ideas how to fix?
I am definitely no expert,but I had the same issue and it turned out to be a defective Pixhawk.
I swapped out the pixhawk and everything was fine.Hope this helps You.
I never had this problem before with this device, so I don´t think it is hardware related.
I also got a new SD card and reflashed the daughter board (flashing arduplane and then back to Arducopter).
All things doesn´t help.