Thank you both for your suggestions. I calibrated the accelerometer and then went out into the yard to calibrate the compass but, could not do that calibration because I could not get good GPS lock. Rather than letting it sit on the stump until GPS stopped going in and out of lock, I shut it down and came back inside. I have a FCB on order from Yuneec Skins. That may be the next step. In thinking back on the behavior of the Typhoon, I have been flying it for quite some time after it reports that it is "ready" and the TX and model have acquired more than a dozen satellites each. The thing is that the model has been blinking that it does not really have GPS lock for those flights, but I blithely ignored the blinking signal because the model always throttled up and took off. It is only recently that it starts its motors but refuses to throttle up and fly. Now that I have re-read the manual and know what that blinking means, I know that the model eventually achieves GPS lock and the light stays green in Smart mode or purple in Angle mode. Its motors start, but it will not take off in Smart or Angle mode even when I have a solid green (Smart) or purple light (Angle). What else could it be except a bad FCB?