hi oretis,
yesterday i was install leos and it work, here's the way
1.download usb driver and the firmware(fw),make sure u download the right fw 3GW100 or 3GW101.
2.install the usb driver file and there will be a warning about the driver and certificated,just install anyway.
3.extract the fw file and you'll find folder with name image folder.
4.connect you phone to computer and make usb connection
5.just copy the image folder your root SDcard,dont be confuse with a root thing, just copy image folder to sdcard, not in any inside folder or anything.
6.disconnect it
7.remember the phone must be >80% battery
the preparation complete now installation upgrade
8.turn off ur phone.
9.push and hold the camera button(in the right side phone) + press the power button, until the screen turn on then release power button, still hold the camera button until in up left screen there will be a text "installation upgrade" and release the camera button and wait(it take 1-2 minute).
10.after the installation proses done, u phone will change to chinese language again and show the confirmation button,choose the left one, and next..next again.
11.change the language and check the software version.
hope this can help U