1. Connect the USB cable from the PC to the TC75 and it will be connected as Media device (MTP).You can see this by swiping from top of the screen to down.
2. If you have KITKAT build (REV A) then copy the SPR28365_TC75_KK_en_1104_v1.zip file to internal or external drive
3. Reboot the device in Recovery mode:
Power Off the device (press and hold power button for 2 seconds; select Power off from menu)
Press and hold Power + Scan key till the TC70 logo appears
4. Device boots into Recovery mode:
Use the Volume up/down key to navigate up and down menu options.
Use the PTT button to select entry.
5. Using Volume down key, navigate to location where SPR28365_TC75_KK_en_1104_v1.zip was placed:
"Apply update from External SD card" or "Apply update from Internal SD card"
Navigate to theSPR28365_TC75_KK_en_1104_v1.zip to apply
6. Press PTT key to select the option
7. Using Volume down key navigate to SPR28365_TC75_KK_SF_5_14_4_signed.zip
8. Press PTT key to select the SPR28365_TC75_KK_en_1104_v1.zip
9. Flashing process will start
10.When The process is complete Select 'Reboot system now option