Tools

Stuck in a bootloop

1. 1

   Get into recovery first

   Hold Power until it force restarts, then use your phone’s key combo, usually Power plus a volume key. Timing can be fiddly, so give it a few goes. If there’s a wipe cache option, try that first, because it leaves your files alone.

2. 2

   Try the other slot

   Newer phones keep two copies of the system. If the bootloader’s unlocked, you can flip to the other one from fastboot. It won’t always boot, especially after a big update, but it’s quick to try.

   fastboot getvar current-slot
   fastboot --set-active=b

   Use whichever of a or b isn’t current.

3. 3

   Reflash what you were running

   Stick to the same build if you can. Unlocked phones can flash images from fastboot. Locked phones can usually only sideload a signed update from stock recovery.

   adb sideload <update>.zip

4. 4

   Factory reset, but only as a last resort

   This fixes a lot of bootloops caused by bad data, but it takes all your files with it. Have a look at saving your files first.

Find your phone’s files

Going back to stock

1. 1

   Get firmware for your exact model and region

   One phone name can cover several models, and their firmware often isn’t interchangeable. Check the model number, not just the name on the box.

2. 2

   Flash it the way it was meant to be flashed

   Follow the instructions that come with it. Some packages have a flash script, others are an update you sideload from recovery. Assume your data’s getting wiped.

3. 3

   Boot it before you touch anything else

   Finish setup and check that calls, Wi-Fi and updates all work. If something’s off, you want to find out now, while the bootloader’s still unlocked.

4. 4

   Only relock if you actually need to

   Relocking on anything other than completely unmodified stock can leave the phone unable to boot, and it wipes your data too. If you’re not sure, leave it unlocked.

   fastboot flashing lock

Find your phone’s files

Grabbing system images

1. 1

   Find the images

   Check the downloads above first. If it’s not there, many full firmware zips keep everything inside a payload.bin, and a payload dumper will split that into separate images.

2. 2

   Boot-level images go through the bootloader

   That’s stuff like boot, init_boot, vendor_boot and dtbo. You’ll need an unlocked bootloader.

   fastboot flash boot boot.img

3. 3

   System partitions go through fastbootd

   On phones with dynamic partitions, system, vendor and product live in a separate userspace fastboot, so a plain bootloader flash won’t work.

   fastboot reboot fastboot
   fastboot flash system system.img

4. 4

   Don’t mix builds

   Images from different builds are a classic way to cause a bootloop, so keep them all from the same one. The exception is a Generic System Image, which is made to run on other devices’ vendor images. Just check it matches your Android version and architecture.

Find your phone’s files

Won’t turn on

1. 1

   Rule out the boring stuff first

   Charge it for 30 minutes with a cable you trust, then hold Power for a good 30 seconds. A fully flat phone can look properly dead.

2. 2

   See what your PC calls it

   Plug it in and look for a new USB device. On Windows check Device Manager, on Linux run lsusb. What it shows tells you what you’re dealing with.

   lsusb | grep -i 05c6

3. 3

   9008 means you’ll probably need an EDL flash

   Shown as QDLoader 9008 or 05c6:9008. The phone is in Qualcomm emergency download mode, which usually means it needs an EDL package with a firehose for your exact model. No firehose, no flash. Plenty of phones also only accept a signed or authorised one, so check that before you start.

4. 4

   900E means fastboot should be in there somewhere

   Shown as Diagnostics 900E or 05c6:900e. You usually aren’t out of options yet, so keep trying to reach fastboot: try different key combos and a few force restarts. If it really won’t get there, you’re back to an EDL package with a firehose, same as 9008.

5. 5

   Nothing shows up at all?

   Try another cable and USB port first, then try a different computer. If it’s still nothing, it may be a hardware problem, so a repair shop or the maker is the next stop.

Find your phone’s files

Saving your files

1. 1

   Try a normal boot first

   Even a phone that crashes after a minute might give you enough time to sync your photos or start a backup. Connect to Wi-Fi and be quick.

2. 2

   Try ADB

   This works if the phone boots far enough and already trusts your computer, or from a custom recovery that can read your data.

   adb devices
   adb pull /sdcard/DCIM

3. 3

   Be realistic about what’s left

   Android encrypts your data, and flashing tools can’t read it unless the phone unlocks it. Skip any paid “recovery” tool promising otherwise. Whatever isn’t backed up may be gone once you wipe.

Find flash tools and drivers

Getting set up

1. 1

   Install platform-tools

   Google’s platform-tools give you adb and fastboot. Grab them from Any phone above, plus a USB driver if you’re on Windows.

2. 2

   Check your phone connects

   Turn on USB debugging in Developer options and accept the prompt on the phone. Then restart to the bootloader and make sure fastboot can see it too.

   adb devices
   adb reboot bootloader
   fastboot devices

3. 3

   Unlock the bootloader, if your phone lets you

   Turn on OEM unlocking in Developer options first. Back up before you do this, because unlocking wipes the phone. Some makers need their own unlock step, and some don’t allow it at all.

   fastboot flashing unlock

Find flash tools and drivers

Installing an OTA

1. 1

   Get the one for your exact model and region

   OTAs are built for one model and region, so double-check both. A phone will usually refuse the wrong one, but don’t count on it.

2. 2

   Check the MD5

   It’s a big download, so make sure it arrived in one piece. Compare the output with the MD5 in the details.

   md5sum <file>

   On Windows: certutil -hashfile <file> MD5

3. 3

   Install it

   Copy it to the phone and use the local install option if your phone has one. Otherwise, sideload it from recovery if your recovery offers that.

   adb sideload <file>

4. 4

   Don’t expect it to go backwards

   OTAs are for moving forward. Going to an older version often needs a special package and a full wipe, so back up first.