Just skip TWRP. Unnecessary.
If your HU is horizontal orientation and 1024x600 or 1280x720 resolution. Your computer package is here. Also download ota zip file (need preloader.bin)
The computer package is missing metazone. Get it from here. MEGA
After you download all the files and unzip them, looks like this (Chinese characters on computer package name removed)
After setting up flash_tool correctly, it looks like this
These are all the files. On the steps to flash firmware (what button to push, when to plug in cable). Watch the video in the guide in post #1399.