RE: B400 with DX7
Well first thing is take off your blades and disconnect the ESC from the motor, leave like 1 connection on, I think you can still hear the beeps that way.
Check that the connectors move the correct way before you put on the blades.
I'd suggest you have a swash mixing issue or travel/trim issue.
The 2 right and left servos should go left and right respectively when giving right stick right and left. When moving forward and back the rear two and front one should move forward and backwards . When moving throttle up all of the servo's should go up. Put in stunt/idle up (BE SURE YOU HAVE DISCO'ed the motor and blades.) Is pitch 0 at mid left stick? Is it positive when you go forward (trailing edge down)? How about moving to low stick on throttle(again in idle up/stunt mode) is trailing edge up, meaning it would fly into the ground?
If not mess with mixes and trim, could also be servo reversed but since you said it went up I assume you mean it went up went pushing throttle up.
DY