I bought a ronin m, after two months without using it, try to charge the batteries but they do not work, none serves, only eh used the Ronin M 3 times, I did not enjoy it, why should this problem with the batteries?

I bought a ronin m, after two months without using it, try to charge the batteries but they do not work, none serves, only eh used the Ronin M 3 times, I did not enjoy it, why should this problem with the batteries?