I can not pair anymore my 4ch pro r2. When turned on, the wifi led flashes very fast for about 2 seconds, then goes off for about a second, then resumes blinking and so on (blink-blink-blink-blink-blink-pause-blink-blink-blink-blink-blink...). Keeping pressed, after switching on, the button on the bottom left for 2 seconds does not cause anything, It always remains in the state just described. Any suggestions ??? Thank you !!