I can't get the new battery for my LG G3 phone to charge.

[Fran Moore]

I have an LG G3 phone that is a little over a year old. It started heating up, and when I took it into the AT&T store where I bought it,I was told that it was the battery. They wanted me to get a new phone, but when I asked if I could just replace the battery, they said I could. The guy at the store took the battery out of my phone so that I could see what to buy. I purchased one off of Amazon, but when I put it in my phone, there was no power. When I plugged it into my charger (the one that came with the phone and that I always use to charge my phone), on the phone screen there appears a yellow triangle with a question mark in it, superimposed over the battery outline, like ti doesn't recognize the type of battery in the phone. It is the same exact type of battery that I have had in the phone.