Heart rate monitor not pairing

Went to use Apple TV and it won’t pair with my heart rate monitor. Tried Zwift on my Android device and it won’t pair with my heart rate monitor either.
Needless to say both had an update today before use

Are you sure that your HRM isn’t already paired with another device? If it’s paired with something else then your Apple TV and phone won’t be able to see it.

Did you pair through the Companion App since ATV limits connections?

It’s paired to other devices but those devices aren’t running at the same time as the Apple TV

I can’t get the companion app to pair either. I’ve only got one device paired on ATV and that’s the smart trainer. It won’t even pick up the heart rate monitor

Accidental paring or forgetting you’ve paired with another device before always give me this trouble. I have 3 possibilities, so I have 1/3 change succeeding before a ride. Usually, I forget to un-pair after a walk with my phone.

checked battery in HRM?