Here I will keep tips on how to debug
Invoking the NuttX Shell
Some insight to operation can be achieved by connected to the USB connection and attaching a hyperterminal to the associated COM port (56Kbaud, 8 bits, no stop bits).
More information at the serial_connection page.
Type “px4io status” at ehe nsh prompt to get a dump of data.
Debugging Startup Problems
At the nsh prompt you can walk through the startup script manually. Starting the the rcS in the ROMFS/px4fmu_common/init.d you can copy and paste each command in succession (or manually type them) to see which cause errors. nsh variables can be viewed with the echo command. Example: echo $RC_FILE
To view fmu parameters use the param command. Example: param show SYS_AUTOCONFIG
type “param” to get a list of other options.