i have the exact same issue when i've uploaded the sketch and adjusted the perameters to use the AruIMU with my DOSD V2+ ... so i'm in the same boat.
I'm having the exact same problem. After power on I get a solid green, solid yellow, and blinking red led.
After that I can't arm the motors, presumably because it is not in stable mode.
Did you figure out a solution?
I figured out why my motors would not arm: the eeprom values where not initialized.
Doing a "reset to factory settings" in the command line interface solved the problem.
The yellow LED is still on solid. Not sure what is up with that yet.