[Droid RAZR M General] lem22:
Minasan, ohayōgozaimasu!

Today we will learn how to upgrade SoftBank's Razr M (201M/XT902) to (semi-)official KitKat.

Note 1: This does work on European GSM incl. Edge and 3G. I cannot test it with anything else, like CDMA or LTE. If it's important for you, please wait until someone else tests it. Of course you could help others by testing is yourself too. If it doesn't work for you, you might also try some of the various guides and apps to enable additional bands on Qualcomm devices (since a band you need is obviously disabled now).

Note 2: After the update there is no Japanese system language anymore (Chinese is).

Disclaimer: No responsibility to any damage caused to your phone, loss of earnings as a result of damaging your phone or anything else that is connected to this guide.

>> TL;DR: Flash Jelly Bean for XT905, update via OTA.

Q: Why this all here?

A: SoftBank won't update the 201M anymore, so it will stay at Jelly Bean forever. On the one hand Jelly Bean is missing functionality (e.g. support for wearables and newer apps), on the other hand it's more vulnerable due to more known security issues. A KitKat bootloader is also needed to install recent CM builds.

Q: How does it work?

A: Motorola released KitKat for the very similar XT905 in Australia. We will just crossflash it's firmware.

Q: Can I downgrade back to the original Jelly Bean?

A: Yes, scroll down.

Prerequisite: a working 201M with an unlocked bootloader. If you need to unlock the bootloader, take a look at this great guide here. Do not continue if your bootloader is locked, since you might end up with a brick.

You ready? Let's go.

0: Backup everything you need! And if you need any of the installed SoftBank apps, make sure to be logged in with the same Google account you want to use after the update. Check that the apps are listed in your "ALL" list in Google Play, so that you can install them again anytime. Still, some of them might not be compatible with KitKat, I don't have a SoftBank account to test them all...

1: Get the latest available complete firmware for the XT905 from here or here.

2: Unzip it, open the XML file with a text editor, delete the lines with partition="partition", partition="tz", and operation="getvar" and save the file.

3: Flash this firmware via the modified XML with RSD Lite. This should take a few minutes.

Ok, now we have the stock XT905 Jelly Bean firmware installed.

Fun fact: you also have a working FM tuner all of a sudden (SoftBank just had no app for it), but just as with Razr i it will be gone in KitKat.

Speaking of which, let's update to KitKat now.

4: Go to "Settings" -> "About phone" -> "System updates". Accept Moto's EULA and let the phone search for updates.

Hey, there's an update!

5: Click on "Download", wait until it's done, and then "Install now". Wait a few more minutes.

6: Factory reset the phone (it's highly recommended). Either with "Setting" -> "Backup & reset" -> "Factory data reset" or even better with RSD Lite and a script like that:

<?xml version="1.0" encoding="UTF-8"?>
<flashing>
<header>
<phone_model model="SCORPION_MINI_U" />
<interfaces>
<interface name="AP" />
</interfaces>
</header>
<steps interface="AP">
<!-- <step operation="getvar" var="max-download-size" /> -->
<step operation="oem" var="fb_mode_set" />
<step operation="erase" partition="modemst1" />
<step operation="erase" partition="modemst2" />
<step operation="erase" partition="tombstones" />
<step operation="erase" partition="userdata" />
<step operation="erase" partition="cache" />
<step operation="oem" var="fb_mode_clear" />
</steps>
</flashing>

7: Restore your backup (if any).

8: Have a Break, Have a Kit Kat.

If you decide to go back to an original SoftBank system, just repeat steps 1–3 with a 201M firmware. There are some factory images here or here.

Even more FAQ:

<reserved>

Have fun!