Having some issues getting the new procedure (fastboot boot twrp.img) to work against Android 8 (to fix the xz2c with xperifix). I have read the FAQ thingie saying to enter blue mode by either doing "adb reboot bootloader" or "fastboot boot bootloader" before flashing vbmeta, followed by fastboot boot twrp.img, however that still doesnt seem to work.
I also remember the procedure used to be different before. I dont recall what it used to be, but the old procedure did work fine, this new one seemingly doesnt.
fastboot boot bootloader
fastboot --disable-verity --disable-verification flash vbmeta vbmeta-xz2c.img
fastboot boot twrp-3.2.3-0-xz2c.img
causes phone to reboot with blue LED still on, then show sony logo, then RED led flashes.. I think 3 times? Then it boots into normal system ("stock" (as in: Sony) android 8) instead of twrp.