Haunted Fire Alarm?

I heard it beeping for 2 days outside my house....I thought it was a work truck in reverse or the garbage truck backing up.....On the early morning of the 3rd day, 5:48am to be exact. I was walking my dog and discovered the beeping was not coming from my neighbor's workers or the garbage truck. I was coming from a hole. Someone had thrown a bag of garbage into the hole at least a year before....it had a generic battery.... the kind that last 1 year.... it was a smoke detector fire alarm....going off in the middle of a garbage bag under thick growth....when I pulled on the bag it totally disintegrated and the smoke detector stopped beeping and flew under the mat I found it under...
Can't explain it..... why did it go off now? how did the battery continue working for all this time? Is someone or something trying to tell me something?
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