So I'm trying to flash adb my android (mostly following this guide), and I'm getting stuck at the unlock device step. I can successfully unlock, but once I reboot my device it reverts to being locked. Apparently I'm unable to continue to the next step without having my device rebooted after it's unlocked.

(I have tried using the volume keys to reboot bootloader, and terminal to reboot it. Neither work.)

I'm using a mac, Samsung Galaxy Nexus, and my initial problem was that my phone was (and still is) stuck in a reboot cycle. I'm pretty sure this was caused by trying to copy too many files to my android via USB cable (not the sd card, I don't have one).

EDIT: So this is exactly what I've been doing.

  1. Open terminal
  2. cd to platform-tools, where I have an up to date adb, fastboot, and a zip file as well as the uncompiled version of image-yakju-jdq39 (Factory Image "yakju" for Galaxy Nexus "maguro" (GSM/HSPA+)).
  3. Volume up+Volume down+ power on (I get a screen with Fastboot mode in red at the bottom, and a picture of an android being operated on. I don't think it matters if I change the "start" thing with the volume buttons, but I'll keep it there.).
  4. Plug the USB cable in.
  5. ./fastboot devices, I get my phones serial number on terminal
  6. ./fastboot oem unlock.
  7. Terminal gives me this: ... OKAY [ 10.016s] finished. total time: 10.016s While on my phone I get the unlock confirmation screen, which I follow through with, and now my phone says it's unlocked (and in blue at the bottom: Fastboot status - OKAY).
  8. ./fastboot reboot starts my phone, but it's clearly still stuck in a bootloop. So I forcefully turn it off, and go back to the fastboot mode, where it's back at the locked status. Is that supposed to happen?

I went ahead with trying to flash my phone anyhow, and it's still stuck in bootloop after this:

usernames-MacBook-Air:~ username$ cd Desktop/adt/sdk/platform-tools
usernames-MacBook-Air:platform-tools username$ ./fastboot devices
014E38590B016008    fastboot
usernames-MacBook-Air:platform-tools username$ ./fastboot oem unlock
OKAY [  9.316s]
finished. total time: 9.316s
usernames-MacBook-Air:platform-tools username$ ./fastboot flash bootloader bootloader-maguro-primelc03.img
sending 'bootloader' (2308 KB)...
OKAY [  0.296s]
writing 'bootloader'...
OKAY [  7.966s]
finished. total time: 8.262s
usernames-MacBook-Air:platform-tools username$ ./fastboot flash radio radio-maguro-i9250xxlj1.img
sending 'radio' (12288 KB)...
OKAY [  1.547s]
writing 'radio'...
OKAY [  4.364s]
finished. total time: 5.910s
usernames-MacBook-Air:platform-tools username$ ./fastboot flash boot boot.img
sending 'boot' (4400 KB)...
OKAY [  0.558s]
writing 'boot'...
OKAY [  2.547s]
finished. total time: 3.106s
usernames-MacBook-Air:platform-tools username$ ./fastboot flash system system.img
erasing 'system'...
OKAY [  0.006s]
sending 'system' (425579 KB)...
OKAY [ 53.344s]
writing 'system'...
OKAY [1502.494s]
finished. total time: 1555.844s
usernames-MacBook-Air:platform-tools username$ ./fastboot flash userdata userdata.img
erasing 'userdata'...
OKAY [  0.031s]
sending 'userdata' (137559 KB)...
OKAY [ 17.258s]
writing 'userdata'...
OKAY [244.587s]
finished. total time: 261.877s
usernames-MacBook-Air:platform-tools username$ ./fastboot flash recovery recovery.img
sending 'recovery' (4900 KB)...
OKAY [  0.620s]
writing 'recovery'...
OKAY [  4.519s]
finished. total time: 5.140s
usernames-MacBook-Air:platform-tools username$ 
  • You haven't successfully unlocked it at all. It's hard to tell what you're trying to achieve from your jumble of wrong commands, but all the times you tried to run fastboot oem unlock it reported a USB error.
    – Dan Hulme
    Sep 23, 2014 at 21:04
  • So how should I fix that USB error? I switched USB ports (the other one doesn't even recognize the phone).
    – RootFAIL
    Sep 24, 2014 at 15:38

1 Answer 1


It seems you are getting an error on the fastboot oem unlock step. If you don't get the bootloader unlocked, then you might as well forget the remaining steps.

To make sure the device is actually in the right mode, I recommend putting it in the bootloader manually. The easiest way to do that is to first turn the phone off. Now hold the volume-up and volume-down buttons, and then press the power button.You'll now see the Android roboto with his front panel open. Check to see that the text below it starts with "FASTBOOT MODE" in red. At the bottom of the screen you may also see the lock/unlock status. Now plug the device into your computer and try the unlock command. If you have a bootloader that shows the lock/unlock status on the device screen, it should change right away. Once you're unlocked, you can proceed with the flash commands. If you get past the unlocking and still have problems, come back with a new question.

  • 1
    OK, so you are definitely in fastboot, and you are definitely still locked. We should now look more closely at the error message you're getting when you do fastboot oem unlock. Can you post the complete messages you see when you do that (looks like you omitted something above because I see ...). Sep 24, 2014 at 16:23
  • 1
    The second argument to fastboot is the partition that you want to flash the image named in the third argument into. I don't think you want to flash a radio image into the recovery partition. If you are wanting to flash the radio, then do fastboot flash radio radio-... Also, you are on a Mac, don't you want to do fastboot-mac? I use Linux exclusively, so I don't know much about that part. However, I do know that you need to flash each image into the right partition or you will run into big trouble. Sep 24, 2014 at 16:50
  • 1
    The device's internal memory is divided into partitions. Typically, these are boot, cache, radio, system, ramdisk, recovery and userdata. Part of the build process generates individual .img files for each of these partitions. You can flash these individually with fastboot flash <partition> <img file>. Sometimes there are scripts like flash-all that take a zip of img files and put them each in the right partition automatically. Sep 24, 2014 at 20:27
  • 1
    Whatever you do though, don't flash an image into the wrong partition. Bad things like bricking can occur. There may be failsafe checks, and maybe the bootloader has the ability to reset everything, but I wouldn't chance it. Sep 24, 2014 at 20:30
  • 1
    When there is a bootloop, it usually means the kernel is panicking, in other words there is something wrong with what you flashed into the boot partition. Double check that you have the correct images for your device. Also, as a sanity check, you might want to try flashing the factory images from developer.android.com. if they don't work, then you probably have a hardware failure. Again, make sure to get the exact correct images for your device and variant. Sep 25, 2014 at 11:37

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .