Sonoff mini r2 frozen - blinking once per second

Hello forum!

I bought 2 sonoff mini r2 and they seem to be frozen - the green LED blinks once per second regardless if I press the button for 5 seconds or more. Because of that I cannot get them in pairing mode and cannot add them in my account…:(.

To be noted that when I shortly press the button the relay works, but I cannot get them to go in pairing more. Any suggestions? Many thanks!