[Pixel C Android Development] WilcoSnel:
Tried several cables and the laptop I'm using has both USB 2.0 and 3.2. Both showing same results in combination with the several cables.

I used latest (139) instead of the one used in your mentioned post (27), does that matter? Or should I use the 27 one? Ran it all again to show the results below.

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot erase userdata
******** Did you mean to fastboot format this ext4 partition?
Erasing 'userdata' (bootloader) erasing flash
FAILED (remote: 'GPT error')
fastboot: error: Command failed

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot erase boot
******** Did you mean to fastboot format this ext4 partition?
Erasing 'boot' (bootloader) erasing flash
FAILED (remote: 'GPT error')
fastboot: error: Command failed

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot erase cache
******** Did you mean to fastboot format this ext4 partition?
Erasing 'cache' (bootloader) erasing flash
FAILED (remote: 'GPT error')
fastboot: error: Command failed

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot erase recovery
******** Did you mean to fastboot format this ext4 partition?
Erasing 'recovery' (bootloader) erasing flash
FAILED (remote: 'GPT error')
fastboot: error: Command failed

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot erase system
******** Did you mean to fastboot format this ext4 partition?
Erasing 'system' (bootloader) erasing flash
FAILED (remote: 'GPT error')
fastboot: error: Command failed

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot flash bootloader bootloader-dragon-google_smaug.7900.139.0.img
Sending 'bootloader' (16384 KB) OKAY [ 0.470s]
Writing 'bootloader' (bootloader) writing flash
OKAY [ 85.294s]
Finished. Total time: 85.811s

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot reboot-bootloader
Rebooting into bootloader OKAY [ 0.000s]
Finished. Total time: 0.000s

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot reboot-bootloader
Rebooting into bootloader OKAY [ 0.000s]
Finished. Total time: 0.000s

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot flash system image-ryu-opm8.190605.005\system.img
Sending sparse 'system' 1/9 (261398 KB) OKAY [ 7.786s]
Writing 'system' (bootloader) writing flash
FAILED (remote: 'GPT error')
fastboot: error: Command failed

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot flash boot image-ryu-opm8.190605.005\boot.img
Warning: skip copying boot image avb footer (boot partition size: 0, boot image size: 9285632).
Sending 'boot' (9068 KB) OKAY [ 0.268s]
Writing 'boot' (bootloader) writing flash
FAILED (remote: 'GPT error')
fastboot: error: Command failed

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot flash recovery image-ryu-opm8.190605.005\recovery.img
Warning: skip copying recovery image avb footer (recovery partition size: 0, recovery image size: 13516800).
Sending 'recovery' (13200 KB) OKAY [ 0.388s]
Writing 'recovery' (bootloader) writing flash
FAILED (remote: 'GPT error')
fastboot: error: Command failed

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot flash cache image-ryu-opm8.190605.005\cache.img
Warning: skip copying cache image avb footer (cache partition size: 0, cache image size: 8388912).
Sending 'cache' (8192 KB) OKAY [ 0.234s]
Writing 'cache' (bootloader) writing flash
FAILED (remote: 'GPT error')
fastboot: error: Command failed

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot flash bootloader bootloader-dragon-google_smaug.7900.139.0.img
Sending 'bootloader' (16384 KB) OKAY [ 0.453s]
Writing 'bootloader' (bootloader) writing flash
OKAY [ 86.056s]
Finished. Total time: 86.540s

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot reboot-bootloader
Rebooting into bootloader OKAY [ 0.000s]
Finished. Total time: 0.000s

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot flash bootloader bootloader-dragon-google_smaug.7900.139.0.img
Sending 'bootloader' (16384 KB) OKAY [ 0.469s]
Writing 'bootloader' (bootloader) writing flash
OKAY [ 86.024s]
Finished. Total time: 86.524s

Locking and unlocking results in the below. Is the 'Enable OEM unlock is not set' error normal if bootloader is unlocked properly? As reported earlier, my 'getvar all' shows no signs of conflicting results of the unlocked status.

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot flashing lock
FAILED (remote: 'Enable OEM unlock is not set')
fastboot: error: Command failed

C:\adb\Pixel C\Stock\ryu-opm8.190605.005>fastboot flashing unlock
FAILED (remote: 'Device already unlocked')
fastboot: error: Command failed

Trying to boot twrp results in the below.

C:\adb\Pixel C>fastboot boot twrp-3.7.0_9-1-dragon.img
creating boot image...
creating boot image - 16918528 bytes
Sending 'boot.img' (16522 KB) OKAY [ 0.469s]
Booting OKAY [ 0.359s]
Finished. Total time: 0.913s

Looks promising right? Except it hangs on the splash screen and after about 10 seconds reboots to the recovery screen :S I even tried every available TWRP version on the site, but to no avail.

I still think if I could somehow restore the sizes of at least the system partition I might start getting somewhere. Does anyone agree with that thought? Or should I be focussing on something else.?

In the meantime I noticed the 'format' command in fastboot help so ran the below after the 'create_logical_partition' returned 'unknown command'. I'm not sure if the formatting is correct. Should I set the size in hex format? Anyway, results of that are below. Maybe someone spots something that could help finding the issue.

C:\adb\Pixel C>fastboot format:ext4:0xe0000000 system
Warning: system size is invalid partition, but 0xe0000000 was requested for formatting.
Couldn't parse erase-block-size '0xunknown variable'.
Couldn't parse logical-block-size '0xunknown variable'.
mke2fs 1.46.6 (1-Feb-2023)
Creating filesystem with 917504 4k blocks and 229376 inodes
Filesystem UUID: 65dbe3d4-3c52-11ee-8b2e-2fcb39ff5447
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736

Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

Warning: skip copying system image avb footer (system partition size: 0, system image size: 110884).
Sending 'system' (108 KB) OKAY [ 0.000s]
Writing 'system' (bootloader) writing flash
FAILED (remote: 'GPT error')
fastboot: error: Command failed

Apologies for the (very) long post, but wanna be thorough :)