If your Android phone is not working or you just want to reinstall the OS, here are some tips on how to do it.

  1. If your phone is powered off, press and hold the power button until the phone turns on and displays “Android” (the Android robot) on the screen.
  2. Tap “Settings” and then “About Phone.”
  3. Tap “Build number” seven times to unlock Developer options.
  4. Go to “Developer options” and turn on USB debugging.
  5. Connect your phone to your computer using a USB cable. The computer should show a message saying that the device is recognized as a storage device (it might also say something like “FTP connection”). If it doesn’t, try connecting your phone using Bluetooth instead.
  6. Open a command prompt (Windows) or terminal (Mac) window and type adb reboot bootloader . This will restart your phone’s bootloader so you can use fastboot commands to flash new firmware or recover data from an existing firmware image file (.img). If you don’t have fastboot installed, you can download it from Google Play Store or Apple App Store . Note: On some phones, you might need to enter fastboot mode by first turning off the screen, then pressing and holding down the Power button until the Android logo appears; release the Power button when Fastboot Mode appears in the bottom left corner of the screen .
  7. Type fastboot oem get_serial_number , where get_serial_number is replaced with either “recovery” or “factory”. For example, if my serial number was 1234567890 , I would type fastboot oem get_serial_number recovery . You’ll see a list of serial numbers after typing this command; find yours and replace “recovery” or “factory” with that number in step 8 below ..