Samsung galaxy s3 not responding?

First of all, I will tell whole history of my smartphone. Actually my s3 got accidently fell from my hand after that lcd became unresponsive, but still motherboard was operating. My brother opened it and had saw a unplug screen connecter. After that mobile started normally. Now my problem started when I had it charged, it showed that battery disconnected so I'd shutdown it after that mobile showed first an empty battery grey tank. Then it showed an empty battery with yellow triangle with single cross drawn on battery. After 2 hours it does even boot up or charge or atleast show same yellow error. I have tried every method that by pulling battery out for ten seconds and plugging in charge and then putting battery back into it. Only one method I have not tried that is putting new battery. I will try it today.
What is the problem with it?
is it dead?(please do not tell me its dead s3 is my whole life)

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