your imu had power or motors wouldn't have started. Id bet you have servo wires mixed or motor direction wrong or wrong direction props or a combination of them, chris
Too little information. Number of flights to date, build process, etc., are all needed to form an opinion. You called out one item incorrectly installed, what else might be installed incorrectly? Props too?
Props were installed correcty. I have been flying this X8 for more than a year (has many hours flying), and in December changed from Naza to wookong (GPS V2) and already had several successful flights.
In the last flights I was having some issue with YAW movements, when only going straight or backwards.