Kessy fob doesn't work.

I bought a car with keys.
Unfortunately one doesn't work. I replaced the batteries. The red LED works- blinking . None of the methods in the manual or the Internet work. Unable to pair the key with the car.
Fob looks good. Each attempt to open the car using the kessy-red LED flashes. Press start stop - red led flashes. There is only information: no key detected...
The key to this is cars. I can open and close it manually
 ..Any idea before I go to Skada servicing and lose my money . 

Thank you .