Cadans and speedsensor No connection with venu 3

Hi,

Since thursday my cadans and speedsensor won’t turn on and wi not connect to my venu 3. I changed the batteries and waited for a few hours to put new batteries back both sensors blinkend red for one or two times and the 10 times green. But when I put the sensors to the pedal and wheel the sensors won’t turn on when I spin them.

anybody has this issue before and know what I can do?