Can someone help me to not have to live that situation again? What should the sensitivity of the gyros should be like the first time?
Is the controller board mounted with the arrow forward?
Is your radio set to 90 degree swash mix if using heli mode?
Did you calibrate the throttle end points?
When you give it throttle, do all the motors start at the same time?
Take the props off, bring the throttle up, now roll, pitch and yaw the tri-copter by hand, can you observe the gyros compensating? I.e. when you roll left, does the left front motor spin up? When you pitch forward, do both front motors spin up? When you yaw right, does the rear servo roll right?
Are your gains set to 50% to start?
What board/firmware are you using?