This is more for my future reference than anything else1. First of all, this model is actually a ZC551KL for which there is an unlock tool at Asus. After enabling Developer Mode and USB debugging, plug the Z01BDC aka ZC551KL to your PC. and follow these steps.
1. Verify that the device is connected to your PC. Typically you'll see it as another drive.
2. Move the downloaded unlock tool from your PC to the Download folder on your device using Windows File Explorer.
3. Tap the APK file to install and run. You will see the device factory reset.
4. Wait for the device to display on-screen set up steps and follow them.
5. Get developer mode and enable USB debugging. Download USB driver if necessary from Phone USB Drivers.
6. Under Settings make a note of the Software information, e.g. WW-126.96.36.199-20170807. The model may still show ASUS_Z01BDC, but don't believe the hype. Ignore and continue.
7. Go to Asus support and download the firmware image that matches step 6. This is precautionary. Hopefully we will not need this download.
9. Download TWRP image to the ADB/Fastboot directory on your PC.
10. Download SuperUser to the ADB and Fastboot directory on your PC. 11. Rename the files recovery.img and su.zip to make the next command line instructions easier to type.
12. Assuming you have ADB and Fastboot installed on your PC, navigate to where you installed Android, ADB and Fastboot for example: C:\Users\SpiFi\AppData\Local\Android\sdk\platform-tools
13. Move the recovery and su files to the ADB and Fastboot directory.
14. Open a command line at that directory and type: "adb reboot bootloader". You should see that the device is unlocked.
15. In same command line window type: fastboot flash recovery recovery.img
16. Open command line window and navigate to the Fastboot and ADB directory, e.g.,