Air tag says it’s beside me but won’t connect to beep so I can find it

I have an AirTag on my dogs collar and it fell off. I followed the last signal to find the last place it moved and says that am I top of it but cannot make it beep to follow the sound and find it in the grass. The only insight online I Find is the battery is dead- it’s not cause it was working until

it fell off. Obviously I cannot change the battery and there is no low battery notification so if that’s the case, how does one know to change it? It worked when I left the house so it should work for the next hour, IMO. come on,Apple you’re better than this, figure it out!!! Now I’m out a collar, air tag and an air tag holder and I’m wondering what the point was in the first place when you can’t locate a lost item unless it is in motion?!! Is the irony lost on me alone? This hadhad it 6 months