Okay, follow this steps to flash the .157 FTF and how to root it. It will take more than an hour (except for the download of FTF) to finish installing the stock ROM. Hope you have the patience to read every steps.
1. Download any .108 FTF, try this
link for the FTF. Or if you can find any .157 FTF, download it. If you find any .157 FTF, skip the
step 5.
2. Make sure all drivers for Z1 is already installed in your PC or Laptop.
3. Next, download the latest flashtool >
here's the link.
4. Install the flashtool and follow this
steps on how to install the FTF by krabappel2548.
5. After you install the FTF, boot the phone and let it configure. then update it to the current .157 FW. Don't worry cause its just a 10mb (i think?) update.
6. Root you're phone using this
method.
7. Download flashable recovery >
use this and look for the latest version, with the name "Z1" on it of course. After you download the file, copy and paste it to your external SD card. (We'll also use this later on installing the 6.2 iHackers ROM)
8. Install a dual recovery via windows, try this
link
9. After you installed the dual recovery via Windows, and i assume that your phone is rebooted to recovery, use the volume rockers to navigate to your extrernal SD card, then look for the flashable dual recovery that you download earlier. then install it. Reboot your device and follow the steps below on how to install the latest 6.2.1 iHackers.