if after doing what @jpgblue indicates it doesn't work,
check volts of the photo, with battery tester disconnected and the charger connected, the value indicated + 3.20 v must be 0
press the power button and at that point the value must be equal to or approximately 3.20 v
If your eMMC is 4GB it will be a little bigger than the photo.
http://imgfz.com/i/JNqQ8ye.jpeg
regards