Opener not working

Hello friends.
I do have an opener and bridge since 4 years and every thing was good. Since some months, it is not any more working and I got the message “ battery state ist critical”. I changed them 3 times but nothing changed. The same statement and when I opened through my app, it is showing opening but not really happening.
I wish I could explain my issue.
I appreciate your support
Regards
Aiham