K/RCQC2 Mini quadcopter kit

I have a question about the K/RCQC2 quadcopter kit. I soldiered everything. But when I try to connect the transmitter with the quadcopter it doesn’t work. The red light is on and the buzzer gives a beep but they don’t connect. I checked every single soldiered part and did it again if there was a little doubt. The only thing I can think about is that I ruined the transmitter. I post photos here so you can see if I did anything wrong.

https://drive.google.com/drive/folders/1_SbzQbJcYwc3Fu8CBB_r-8N_pVkFrwZB

Thanks!

Please check you’re solder points,
Try reheating the pad and the pin at the same time.

I have also bought this quadcopter kit and have the same problem. Have the advice from VEL337 helped you? Because I am already reading about anew kit at https://themybuy.com/best-diy-rc-quadcopter-kit/. Want to buy something better and more expensive.