Chosen Solution
One day I was charging my phone and it just turned off and went into a boot loop so I looked up some tips online and they told me to just restore it. I was told to put the iPhone on the screen with the iTunes logo and restore but when I tried it gave me error 21 then error 2009 and when it restores it powers off and goes right back to the apple screen. Plus it will not turn on without a USB and even though I bought a new battery and replaced it the phone is still does the same thing.
when the os does not load and all you get is the logo repeatedly booting: 1 pop out the back plate, and then the screw connecting the battery. 2 just unplug the sensor cable and snap it back in. make sure the iPhone is connected to a power source (though not pertinent if the battery has enough juice) From (iPhone4 won’t restore and shows Error 21)
