How to turn on the F3? Usually you can hold the mode and start button to turn it on. Although this method works for all this kind of products, occasionally, when you receive your F3, you can’t turn it on with this method, don’t worry. there is a way to solve it.
This is not the hardware issue, but the bad contact of power button. This video will show you how to deal with it.
OK, generally you just need to take off the back cover, then take the chip out, hold the mode and start button until the screen lights up. Then you can put it back, be careful, the four buttons should be fit well with the frame.