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Hi, Ive bought an “Iphone 4 remplacement battery kit” on ifixit, Ive placed the new battery in the phone, but its show the itunes logo and when i try to restore the iphone, it shows the error 2001. When i unplugg the iphone, he turn off immediately But, when i try to put the old battery, the phone work well! Does anyone have the same problem? Otherwise i conclude the battery sell by ifixit don’t work… (sorry for my broken english)

English is not a problem, when compared to our iPhone problems. Coming to point. The battery you replaced (that is the new one) is out of charge. Get a new battery or boost the charge using DC regulator externally to the new battery.