Looks like a weak motor or you didnt do the gyro synchronization.
Put it on a very level surface, turn on the quad, wait for the lights to go from fast to slow blink...then turn on the transmitter.
Push the throttle all the way up then all the way down ( the quad should now be linked to the transmitter)
Next, pull BOTH sticks down to the lower right corners. The lights on the X5C-1 should go into a fast blinking.
Hold the sticks in the lower right corners until the blinking stops.
You have successfully calibrated the gyros.
Try it again. If good, you're done.
If not.......
Re check that all props are spinning the correct way. Like a fan, they must spin so that they blow DOWNWARD.
Check to be sure all props spin freely.
If you were to post a video from DIRECTLY above the quad while slowly advancing the throttle a few times
I could probably see the bad motor. (If that's the issue).
Mine arrived with one motor completely not working. I opening it up and found a motor wire completely hanging loose.
Quick and easy fix. Been flying great ever since.
It is possible that it's the transmitter but I doubt it. Read the manual on how to TRIM the controls.
Make sure none are trimmed all the way in one direction.
The last possibility is a bad controller board. They're about $10.
WELL worth the replacement if necessary.