Original post by: Seji the veggie ,
Where exactly did you get the battery from? If it's not up to spec, or it can't communicate with the phone, it won't work. Some batteries CLAIM to be compatible, but contain the wrong number of cells, the wrong type of cells, or the improper wiring. Additionally, cheap batteries may not have the proper safety certification, posing a serious fire or explosion risk. iFixit's [product|IF118-001-2] has all the pertinent safety information, as well as validation for power specs.