mainboard problem of crazyflie2

[Sherry]

When I assemble a crazyflie2 and use client to refresh firmware on it, its blue led light is always on, no matter how to press the on/off button, it doesn't work. What is the cause of this? Thanks!

[tobias]

Where did you buy it? Looks like a clone!

Try a cold boot recovery as linked to in the end of this post.