[General Questions and Answers] LinuxHippy:
I just bought a Sony Xperia XZ1 G8342 off eBay that was sold saying that it was Google locked. I've been flashing phones for years with the help of XDA and figured I would just get it into recovery and wipe the software or use ADB from my Linux computer. Both methods have proven difficult, though, as there isn't a recovery system that I can get to on this Sony Xperia XZ1. I would like to install a custom ROM on this phone but to do that it has to have the bootloader unlocked and I did find that it is still locked using fastboot, however the phone won't let me get into settings to enable USB debugging which is what Sony developers want u to do in this guide:

Sony Developers Guide-unlock bootloader

Now I can get this phone into fastboot mode by having the phone powered off, pressing volume up and plugging in a usb cable from my computer at the same time. Then the LED turns blue and fastboot devices doesn't return an error.

So, do I need to have USB debugging enabled on the phone (or maybe somebody else already did this) if I don't get a fastboot error?

I was able to get this long output from fastboot getvar all:

(bootloader) hw-revision:20001
(bootloader) unlocked:no
(bootloader) off-mode-charge:0
(bootloader) charger-screen-enabled:0
(bootloader) battery-soc-ok:yes
(bootloader) battery-voltage:4324
(bootloader) version-baseband:1307-7471_47.2.A.11.228
(bootloader) version-bootloader:1306-5035_X_Boot_MSM8998_LA2.0_P_114
(bootloader) erase-block-size: 0x1000
(bootloader) logical-block-size: 0x1000
(bootloader) variant:MSM UFS
(bootloader) partition-type:xblbak:raw
(bootloader) partition-size:xblbak: 0x3F5000
(bootloader) partition-type:xbl:raw
(bootloader) partition-size:xbl: 0x3F5000
(bootloader) partition-type:userdata:ext4
(bootloader) partition-size:userdata: 0xCFA976000
(bootloader) partition-type:system:ext4
(bootloader) partition-size:system: 0x138800000
(bootloader) partition-type:vendor:raw
(bootloader) partition-size:vendor: 0x60000000
(bootloader) partition-type:oem:raw
(bootloader) partition-size:oem: 0x19000000
(bootloader) partition-type:rdimage:raw
(bootloader) partition-size:rdimage: 0x2000000
(bootloader) partition-type:fsmetadata:raw
(bootloader) partition-size:fsmetadata: 0x101000
(bootloader) partition-type:Qnovo:raw
(bootloader) partition-size:Qnovo: 0x1800000
(bootloader) partition-type:diag:raw
(bootloader) partition-size:diag: 0x2000000
(bootloader) partition-type:appslog:raw
(bootloader) partition-size:appslog: 0x1000000
(bootloader) partition-type:vbmeta:raw
(bootloader) partition-size:vbmeta: 0x10000
(bootloader) partition-type:frp:raw
(bootloader) partition-size:frp: 0x80000
(bootloader) partition-type:keystore:raw
(bootloader) partition-size:keystore: 0x80000
(bootloader) partition-type:misc:raw
(bootloader) partition-size:misc: 0x100000
(bootloader) partition-type:cache:ext4
(bootloader) partition-size:cache: 0x17C00000
(bootloader) partition-type:ssd:raw
(bootloader) partition-size:ssd: 0x2000
(bootloader) partition-type:fsc:raw
(bootloader) partition-size:fsc: 0x1000
(bootloader) partition-type:modemst2:raw
(bootloader) partition-size:modemst2: 0x200000
(bootloader) partition-type:modemst1:raw
(bootloader) partition-size:modemst1: 0x200000
(bootloader) partition-type:ddr:raw
(bootloader) partition-size:ddr: 0x100000
(bootloader) partition-type:FOTAKernel:raw
(bootloader) partition-size:FOTAKernel: 0x4000000
(bootloader) partition-type:logfs:raw
(bootloader) partition-size:logfs: 0x800000
(bootloader) partition-type:toolsfv:raw
(bootloader) partition-size:toolsfv: 0x100000
(bootloader) partition-type:limits:raw
(bootloader) partition-size:limits: 0x1000
(bootloader) partition-type:splash:raw
(bootloader) partition-size:splash: 0x20A4000
(bootloader) partition-type:dpo:raw
(bootloader) partition-size:dpo: 0x1000
(bootloader) partition-type:msadp:raw
(bootloader) partition-size:msadp: 0x40000
(bootloader) partition-type:apdp:raw
(bootloader) partition-size:apdp: 0x40000
(bootloader) partition-type:bluetooth:raw
(bootloader) partition-size:bluetooth: 0x100000
(bootloader) partition-type:boot:raw
(bootloader) partition-size:boot: 0x4000000
(bootloader) partition-type:dsp:raw
(bootloader) partition-size:dsp: 0x1000000
(bootloader) partition-type:modem:raw
(bootloader) partition-size:modem: 0x6E00000
(bootloader) partition-type:sec:raw
(bootloader) partition-size:sec: 0x4000
(bootloader) partition-type:fsg:raw
(bootloader) partition-size:fsg: 0x180000
(bootloader) partition-type:persist:raw
(bootloader) partition-size:persist: 0x2000000
(bootloader) partition-type:xflkeystorebak:raw
(bootloader) partition-size:xflkeystorebak: 0x20000
(bootloader) partition-type:xflkeystore:raw
(bootloader) partition-size:xflkeystore: 0x20000
(bootloader) partition-type:tzxflbak:raw
(bootloader) partition-size:tzxflbak: 0x80000
(bootloader) partition-type:tzxfl:raw
(bootloader) partition-size:tzxfl: 0x80000
(bootloader) partition-type:tzxflattestbak:raw
(bootloader) partition-size:tzxflattestbak: 0x80000
(bootloader) partition-type:tzxflattest:raw
(bootloader) partition-size:tzxflattest: 0x80000
(bootloader) partition-type:xflbak:raw
(bootloader) partition-size:xflbak: 0x1E00000
(bootloader) partition-type:xfl:raw
(bootloader) partition-size:xfl: 0x1E00000
(bootloader) partition-type:storsecbak:raw
(bootloader) partition-size:storsecbak: 0x20000
(bootloader) partition-type:storsec:raw
(bootloader) partition-size:storsec: 0x20000
(bootloader) partition-type:devcfgbak:raw
(bootloader) partition-size:devcfgbak: 0x20000
(bootloader) partition-type:devcfg:raw
(bootloader) partition-size:devcfg: 0x20000
(bootloader) partition-type:sti:raw
(bootloader) partition-size:sti: 0x200000
(bootloader) partition-type:cmnlib64bak:raw
(bootloader) partition-size:cmnlib64bak: 0x80000
(bootloader) partition-type:cmnlib64:raw
(bootloader) partition-size:cmnlib64: 0x80000
(bootloader) partition-type:cmnlibbak:raw
(bootloader) partition-size:cmnlibbak: 0x80000
(bootloader) partition-type:cmnlib:raw
(bootloader) partition-size:cmnlib: 0x80000
(bootloader) partition-type:keymasterbak:raw
(bootloader) partition-size:keymasterbak: 0x80000
(bootloader) partition-type:keymaster:raw
(bootloader) partition-size:keymaster: 0x80000
(bootloader) partition-type:devinfo:raw
(bootloader) partition-size:devinfo: 0x1000
(bootloader) partition-type:ablbak:raw
(bootloader) partition-size:ablbak: 0x180000
(bootloader) partition-type:abl:raw
(bootloader) partition-size:abl: 0x180000
(bootloader) partition-type:pmicbak:raw
(bootloader) partition-size:pmicbak: 0x80000
(bootloader) partition-type:pmic:raw
(bootloader) partition-size:pmic: 0x80000
(bootloader) partition-type:hypbak:raw
(bootloader) partition-size:hypbak: 0x80000
(bootloader) partition-type:hyp:raw
(bootloader) partition-size:hyp: 0x80000
(bootloader) partition-type:tzbak:raw
(bootloader) partition-size:tzbak: 0x200000
(bootloader) partition-type:tz:raw
(bootloader) partition-size:tz: 0x200000
(bootloader) partition-type:rpmbak:raw
(bootloader) partition-size:rpmbak: 0x80000
(bootloader) partition-type:rpm:raw
(bootloader) partition-size:rpm: 0x80000
(bootloader) partition-type:LTALabel:raw
(bootloader) partition-size:LTALabel: 0x1000000
(bootloader) partition-type:TA:raw
(bootloader) partition-size:TA: 0x200000
(bootloader) secure:yes
(bootloader) product:G8342
(bootloader) max-download-size:536870912
(bootloader) kernel:uefi