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I used to have an Android developer phone (an ancient HTC Innovation) that I recently gave to a friend. Now we're trying to unlock it so he can use it. We put in the unlock password too many times, so now the phone is asking us for my Google password, even if we turn the phone on and off again. Unfortunately, the phone doesn't have Internet access and I changed my Google account password since the last time I used the phone, so I have no idea what password to put in to unlock it.

How can we unlock or factory reset the phone so my friend can use it?

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If fastboot is installed on the handset (or commonly called bootloader), it might be best to re-flash via usage of USB cable and the handset with the cable plugged in.

In order to achieve this, a original image file is needed for this to work. The essence of fastboot, is that from the command line, the handset can be re-formatted and told to boot specific kernels without touching the original on the handset.

Consider the options used in the fastboot binary command line application, as in:

usage: fastboot [ <option> ] <command>

  update <filename>                        reflash device from
  flashall                                 flash boot + recovery + system
  flash <partition> [ <filename> ]         write a file to a flash partition
  erase <partition>                        erase a flash partition
  getvar <variable>                        display a bootloader variable
  boot <kernel> [ <ramdisk> ]              download and boot kernel
  flash:raw boot <kernel> [ <ramdisk> ]    create bootimage and flash it
  devices                                  list all connected devices
  continue                                 continue with autoboot
  reboot                                   reboot device normally
  reboot-bootloader                        reboot device into bootloader
  help                                     show this help message

  -w                                       erase userdata and cache
  -s <serial number>                       specify device serial number
  -p <product>                             specify product name
  -c <cmdline>                             override kernel commandline
  -i <vendor id>                           specify a custom USB vendor id
  -b <base_addr>                           specify a custom kernel base address
  -n <page size>                           specify the nand page size. default: 2048

Thus, the command line to wipe cleanly and flash the original image file would be this:

  1. fastboot erase system to wipe the /system partition cleanly.
  2. fastboot erase data to wipe the /data partition cleanly.
  3. fastboot flash system original_system_image.img

The optional step may as well be, to flash the original boot image which can be achieved in this manner - fastboot flash boot original_boot_image.img.

If you happen to have the original for your handset, it might be easier to do it in this fashion, instead of the three steps above listed, as in fastboot update

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I haven't worked with Android bootloaders before. How do I get access to the command line interface? – Kevin Dec 19 '12 at 3:24
Power off phone (remove and replace battery, etc.), hold down volume down and power. Then for command line you run fastboot on computer. That shouldn't be needed, however. The boot menu on the phone usually offers factory reset right from the boot menu you'll be in... – Lance Nanek Dec 19 '12 at 16:58

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