1- Get a working datacable and test it with any piece of Z5 software.

2- Download the GL3 flash loader from 'Programs' page and extract the two files to any directory.

3- Download the Z5 firmware file from 'Firmwares' page and extract the SRE file to any directory.

4- Make sure that the battery has a high level of charge. Power down your phone and connect it.

5- Run the GL3 flash loader and define the correct settings. If you have trouble with 115200bps, try 38400bps.

6- Make sure that the load option is set to 'Download to Mobile'. Then, click 'Start' and select the SRE firmware file.

7- You should see 'Power up mobile' now, so press the power button on your phone shortly and keep your eye on the computer screen.

8- The phone won't seem to do anything, but flashing should start. You'll see an indicator on the flash loader that shows how much of the file has been processed or transferred already.

9- When flashing is done, disconnect your phone and power it on. It will not power on before disconnecting it, so don't worry. Check your new firmware by typing *#release#.

10- If your phone doesn't power on, then the firmware file you transferred is likely to be corrupted. You'll need to reflash the phone with another working file.