"I have a same problems. I have to connect OSD or XBEE before board can boot up. And I wonder why no one from development team answer this question.???"
"What's battery you use. I'm use Gaui 330x-s frame too. With 2200mAh (2S) it work perfect with default PID. No need to tune up. But when change battery to 2200mAh (3S) it cause oscillation.