I have same issues. I bought a new battery and it worked for awhile. Then battery is not getting charged again. I decided to buy huwaei phone instead. So far I am very happy with it. I'm staying away from any Blu phones from now on.
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=== Update (08/19/2017) ===
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I just found a way to charge battery. Yes it's the faulty charging port. You can buy a universal battery charger and charge battery separately or you can use same USB cable, cut the one going to the phone port, strip the cables, remove the tin foil protection, the red colored wire goes to positive of battery and the aluminum strands/ silver colored goes to negative terminal. Use a small strip of Scotch tapes to attach each wires separately to positive and negative terminal s, don't let them touch. Then insert battery back into phone. The positive and negative prongs will push each wires tightly to the battery terminal. Plug the charger to the wall. Let it charge overnight. Once completely charged, remove battery again, remove wires, insert battery again and turn cellphone on. My phone worked. But I will definitely stay away from blu phones from now on. I bought Huawei mate 2 phone and updated the operating system.
I have same issues. I bought a new battery and it worked for awhile. Then battery is not getting charged again. I decided to buy huwaei phone instead. So far I am very happy with it. I'm staying away from any Blu phones from now on.