After the pitch pot to zero, 4 blink then endless blinking above now the board won't arm at all. I wish this thing had better documentation!
I finally flashed the board again to get back to square one and now am at the original isse, won't arm when rudder is plugged in, unplug, arms, plug back in and will fly fine.
I've also tried leaving the rudder plugged in with dual rates set to 100% for all channels, and even then throttle and yaw trim down/right, then holding the stick down/right for 5 seconds, no go.
Then with 80% DR and centered trims the plug/unplug trick works. Grrr..