This is what happens when I try to flash TWRP, following instructions from XDA-devs:
I connect the Xperia X’s usb to my PC while holding the “volume up” button. LED turns red for a second, then blue. I run these commands:
[ben@catull-mnj ~]$ adb reboot bootloader
* daemon not running; starting now at tcp:5037
* daemon started successfully
error: no devices/emulators found
[ben@catull-mnj ~]$ adb devices
List of devices attached
// <= emtpy line here
So there is behavior as if fastboot isn’t recognizing my device. But, now I try to flash recovery anyways:
[ben@catull-mnj ~]$ fastboot flash recovery /mnt/RedData/ISO-images/Xperia-X/twrp-3.3.1-0-suzu.img
Sending 'recovery' (21824 KB) OKAY [ 0.735s]
Writing 'recovery' OKAY [ 0.155s]
Finished. Total time: 0.902s
[ben@catull-mnj ~]$ fastboot reboot
Rebooting OKAY [ 0.001s]
Finished. Total time: 0.052s
Voila, TWRP is flashed, even though fastboot first pretended it wasn’t seeing any devices.
This last reboot leads to the black-on-white Sony logo, device becomes unresponsive. I hold power + volume up until three vibrations to power it off.
I boot to TWRP by holding power button and volume up.
Wiping as in the instructions posted above:
i.e., I did first “Format Data” and then at Advanced Wipe, I checked
Dalvik / ART Cache
System
Cache
Leads to this: