Hey all, long time lurker to these forums. Just thought I would share that the F880 series and possibly the ZX1 can still be rooted. I came across a Japanese YouTube video showing the root process for an F886 with 1.24.0000 firmware. It involves using the KingRoot software and installing SuperSU instead of the KingRoot app. I tried it myself on my F887 and can confirm it works! Since I couldn't read Japanese, I just followed along with the video and used the links in the description.
Link to video:
http://www.youtube.com/watch?v=N_F4Ef7fBo0
You might want to enable usb debugging after enabling developer options (I'm not sure you really need to do this, but it couldn't hurt)
http://www.greenbot.com/article/2457986/how-to-enable-developer-options-on-your-android-phone-or-tablet.html
Steps I've deciphered from watching the video:
1) Download and install the KingRoot software for Windows from
http://www.kingroot.net (the software is completely in Chinese language unfortunately)
2) Start up the KingRoot software (if it hasn't already started up already) and plug in your F880 series walkman. It should be detecting your device and downloading root exploits for it.
3) When it's done finding the root exploit for your device, click on the green Root button and it should start rooting your device. (the device should restart a couple of times)
4) Rooting should be finished when the program shows a big green check mark and KingRoot app launches on the device.
5) Close the KingRoot app since we'll be installing SuperSU instead.
6) Go to:
http://www.w0lfdroid.com/2015/05/How-to-Remove-Replace-KingUser-KingRoot-with-SuperSU.html?m=1 and download [COLOR=555555]Replace_Kingroot_With_SuperSU.zip at the bottom of the page.[/COLOR]
[COLOR=555555]7) Extract Replace_Kingroot_With_SuperSU.zip and there should be a folder named "mrw". Move the "mrw" folder to the root directory of the device. You can disconnect the device from the computer after the "mrw" folder is done copying and close the KingRoot program on the computer.[/COLOR]
[COLOR=555555]8) Open up the Google Play store and download/install "Terminal Emulator for Android".[/COLOR]
[COLOR=555555]9) Start up Terminal Emulator and type the following:[/COLOR]
[COLOR=555555]su[/COLOR]
(hit enter and press "allow" when the pop up appears)
[COLOR=555555]sh /sdcard/mrw/root.sh[/COLOR]
[COLOR=555555](hit enter, the script should run and there should be a whole lot of failures, it should also crash)[/COLOR]
[COLOR=555555]10) Press OK, and SuperSU should start up. Press "Normal" and SuperSU should start to install. Press OK again the next 2 times when the pop up appears.[/COLOR]
Congratulations! Your F880 should now be rooted! Now you can install awesome stuff like Viper4Android, Xposed, and a bunch of battery saving apps such as Greenify and Amplify.