[E 2015 Q&A, Help & Troubleshooting] Sher1234:
Restoring to stock 6.0 was unsuccessful

on XT1521

the device is not booting to system only loops recovery (& which is even twrp which should be removed after flashing stock)

Here's a CMD log for the restore

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot oem fb_mode_set

...

OKAY [ 0.133s]

finished. total time: 0.135s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash partition gpt.bin

(bootloader) has-slot:partition: not found

target reported max download size of 268435456 bytes

sending 'partition' (32 KB)...

OKAY [ 0.008s]

writing 'partition'...

(bootloader) This may take a few seconds, if a

(bootloader) different partition table is being

(bootloader) flashed since we need to backup

(bootloader) and restore a few partitions

(bootloader) Flashing primary GPT image...

(bootloader) Flashing backup GPT image...

OKAY [ 0.893s]

finished. total time: 0.904s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash bootloader bootloader.img

(bootloader) has-slot:bootloader: not found

target reported max download size of 268435456 bytes

sending 'bootloader' (2410 KB)...

OKAY [ 0.086s]

writing 'bootloader'...

(bootloader) flashing sbl1 ...

(bootloader) flashing aboot ...

(bootloader) flashing tz ...

(bootloader) flashing hyp ...

(bootloader) flashing rpm ...

OKAY [ 1.350s]

finished. total time: 1.439s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash logo logo.bin

(bootloader) has-slot:logo: not found

target reported max download size of 268435456 bytes

sending 'logo' (679 KB)...

OKAY [ 0.029s]

writing 'logo'...

OKAY [ 0.058s]

finished. total time: 0.090s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash boot boot.img

(bootloader) has-slot:boot: not found

target reported max download size of 268435456 bytes

sending 'boot' (32768 KB)...

OKAY [ 1.098s]

writing 'boot'...

OKAY [ 0.994s]

finished. total time: 2.094s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash recovery recovery.img⁠

(bootloader) has-slot:recovery: not found

error: cannot load 'recovery.img?'

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.0

(bootloader) has-slot:system: not found

target reported max download size of 268435456 bytes

sending 'system' (262126 KB)...

OKAY [ 8.489s]

writing 'system'...

OKAY [ 6.735s]

finished. total time: 15.230s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.1

(bootloader) has-slot:system: not found

target reported max download size of 268435456 bytes

sending 'system' (244589 KB)...

OKAY [ 7.920s]

writing 'system'...

OKAY [ 5.851s]

finished. total time: 13.774s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.2

(bootloader) has-slot:system: not found

target reported max download size of 268435456 bytes

sending 'system' (254084 KB)...

OKAY [ 8.222s]

writing 'system'...

OKAY [ 6.010s]

finished. total time: 14.235s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.3

(bootloader) has-slot:system: not found

target reported max download size of 268435456 bytes

sending 'system' (258938 KB)...

OKAY [ 8.387s]

writing 'system'...

OKAY [ 11.416s]

finished. total time: 19.806s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.4⁠⁠⁠⁠

(bootloader) has-slot:system: not found

error: cannot load 'system.img_sparsechunk.4????'

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash modem NON-HLOS.bin

(bootloader) has-slot:modem: not found

target reported max download size of 268435456 bytes

sending 'modem' (55540 KB)...

OKAY [ 1.806s]

writing 'modem'...

OKAY [ 3.325s]

finished. total time: 5.134s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase modemst1

(bootloader) has-slot:modemst1: not found

erasing 'modemst1'...

OKAY [ 0.017s]

finished. total time: 0.018s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase modemst2

(bootloader) has-slot:modemst2: not found

erasing 'modemst2'...

OKAY [ 0.016s]

finished. total time: 0.018s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash fsg fsg.mbn

(bootloader) has-slot:fsg: not found

target reported max download size of 268435456 bytes

sending 'fsg' (1527 KB)...

OKAY [ 0.057s]

writing 'fsg'...

OKAY [ 0.105s]

finished. total time: 0.164s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase cache

(bootloader) has-slot:cache: not found

erasing 'cache'...

OKAY [ 0.024s]

finished. total time: 0.025s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase userdata

(bootloader) has-slot:userdata: not found

erasing 'userdata'...

OKAY [ 0.978s]

finished. total time: 0.980s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase customize

(bootloader) has-slot:customize: not found

erasing 'customize'...

(bootloader) Invalid partition name customize

FAILED (remote failure)

finished. total time: 0.012s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot oem fb_mode_clearfastboot oem fb_mode_set

...

(bootloader) 'fb_mode_clearfastboot' is not a supported oem command

(bootloader) See 'fastboot oem help'

FAILED (remote failure)

finished. total time: 0.021s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash partition gpt.bin

(bootloader) has-slot:partition: not found

target reported max download size of 268435456 bytes

sending 'partition' (32 KB)...

OKAY [ 0.008s]

writing 'partition'...

(bootloader) This may take a few seconds, if a

(bootloader) different partition table is being

(bootloader) flashed since we need to backup

(bootloader) and restore a few partitions

(bootloader) Flashing primary GPT image...

(bootloader) Flashing backup GPT image...

OKAY [ 0.728s]

finished. total time: 0.739s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash bootloader bootloader.img

(bootloader) has-slot:bootloader: not found

target reported max download size of 268435456 bytes

sending 'bootloader' (2410 KB)...

OKAY [ 0.087s]

writing 'bootloader'...

(bootloader) flashing sbl1 ...

(bootloader) flashing aboot ...

(bootloader) flashing tz ...

(bootloader) flashing hyp ...

(bootloader) flashing rpm ...

OKAY [ 1.354s]

finished. total time: 1.443s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash logo logo.bin

(bootloader) has-slot:logo: not found

target reported max download size of 268435456 bytes

sending 'logo' (679 KB)...

OKAY [ 0.029s]

writing 'logo'...

OKAY [ 0.047s]

finished. total time: 0.079s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash boot boot.img

(bootloader) has-slot:boot: not found

target reported max download size of 268435456 bytes

sending 'boot' (32768 KB)...

OKAY [ 1.099s]

writing 'boot'...

OKAY [ 0.786s]

finished. total time: 1.887s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash recovery recovery.img⁠

(bootloader) has-slot:recovery: not found

error: cannot load 'recovery.img?'

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.0

(bootloader) has-slot:system: not found

target reported max download size of 268435456 bytes

sending 'system' (262126 KB)...

OKAY [ 8.485s]

writing 'system'...

OKAY [ 6.716s]

finished. total time: 15.203s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.1

(bootloader) has-slot:system: not found

target reported max download size of 268435456 bytes

sending 'system' (244589 KB)...

OKAY [ 7.926s]

writing 'system'...

OKAY [ 5.848s]

finished. total time: 13.777s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.2

(bootloader) has-slot:system: not found

target reported max download size of 268435456 bytes

sending 'system' (254084 KB)...

OKAY [ 8.237s]

writing 'system'...

OKAY [ 6.000s]

finished. total time: 14.241s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.3

(bootloader) has-slot:system: not found

target reported max download size of 268435456 bytes

sending 'system' (258938 KB)...

OKAY [ 8.390s]

writing 'system'...

OKAY [ 6.092s]

finished. total time: 14.486s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.4⁠⁠⁠⁠

(bootloader) has-slot:system: not found

error: cannot load 'system.img_sparsechunk.4????'

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash modem NON-HLOS.bin

(bootloader) has-slot:modem: not found

target reported max download size of 268435456 bytes

sending 'modem' (55540 KB)...

OKAY [ 1.807s]

writing 'modem'...

OKAY [ 1.367s]

finished. total time: 3.176s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase modemst1

(bootloader) has-slot:modemst1: not found

erasing 'modemst1'...

OKAY [ 0.018s]

finished. total time: 0.019s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase modemst2

(bootloader) has-slot:modemst2: not found

erasing 'modemst2'...

OKAY [ 0.016s]

finished. total time: 0.018s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash fsg fsg.mbn

(bootloader) has-slot:fsg: not found

target reported max download size of 268435456 bytes

sending 'fsg' (1527 KB)...

OKAY [ 0.057s]

writing 'fsg'...

OKAY [ 0.065s]

finished. total time: 0.125s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase cache

(bootloader) has-slot:cache: not found

erasing 'cache'...

OKAY [ 0.018s]

finished. total time: 0.020s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase userdata

(bootloader) has-slot:userdata: not found

erasing 'userdata'...

OKAY [ 0.059s]

finished. total time: 0.061s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase customize

(bootloader) has-slot:customize: not found

erasing 'customize'...

(bootloader) Invalid partition name customize

FAILED (remote failure)

finished. total time: 0.013s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot oem fb_mode_clearfastboot oem fb_mode_set

...

(bootloader) 'fb_mode_clearfastboot' is not a supported oem command

(bootloader) See 'fastboot oem help'

FAILED (remote failure)

finished. total time: 0.021s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash partition gpt.bin

(bootloader) has-slot:partition: not found

target reported max download size of 268435456 bytes

sending 'partition' (32 KB)...

OKAY [ 0.008s]

writing 'partition'...

(bootloader) This may take a few seconds, if a

(bootloader) different partition table is being

(bootloader) flashed since we need to backup

(bootloader) and restore a few partitions

(bootloader) Flashing primary GPT image...

(bootloader) Flashing backup GPT image...

OKAY [ 0.652s]

finished. total time: 0.662s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash bootloader bootloader.img

(bootloader) has-slot:bootloader: not found

target reported max download size of 268435456 bytes

sending 'bootloader' (2410 KB)...

OKAY [ 0.087s]

writing 'bootloader'...

(bootloader) flashing sbl1 ...

(bootloader) flashing aboot ...

(bootloader) flashing tz ...

(bootloader) flashing hyp ...

(bootloader) flashing rpm ...

OKAY [ 1.346s]

finished. total time: 1.436s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash logo logo.bin

(bootloader) has-slot:logo: not found

target reported max download size of 268435456 bytes

sending 'logo' (679 KB)...

OKAY [ 0.029s]

writing 'logo'...

OKAY [ 0.047s]

finished. total time: 0.079s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash boot boot.img

(bootloader) has-slot:boot: not found

target reported max download size of 268435456 bytes

sending 'boot' (32768 KB)...

OKAY [ 1.101s]

writing 'boot'...

OKAY [ 0.782s]

finished. total time: 1.887s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash recovery recovery.img⁠

(bootloader) has-slot:recovery: not found

error: cannot load 'recovery.img?'

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.0

(bootloader) has-slot:system: not found

target reported max download size of 268435456 bytes

sending 'system' (262126 KB)...

OKAY [ 8.491s]

writing 'system'...

OKAY [ 6.730s]

finished. total time: 15.225s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.1

(bootloader) has-slot:system: not found

target reported max download size of 268435456 bytes

sending 'system' (244589 KB)...

OKAY [ 7.926s]

writing 'system'...

OKAY [ 5.852s]

finished. total time: 13.781s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.2

(bootloader) has-slot:system: not found

target reported max download size of 268435456 bytes

sending 'system' (254084 KB)...

OKAY [ 8.229s]

writing 'system'...

OKAY [ 6.013s]

finished. total time: 14.245s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.3

(bootloader) has-slot:system: not found

target reported max download size of 268435456 bytes

sending 'system' (258938 KB)...

OKAY [ 8.386s]

writing 'system'...

OKAY [ 6.076s]

finished. total time: 14.482s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash system system.img_sparsechunk.4⁠⁠⁠⁠

(bootloader) has-slot:system: not found

error: cannot load 'system.img_sparsechunk.4????'

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash modem NON-HLOS.bin

(bootloader) has-slot:modem: not found

target reported max download size of 268435456 bytes

sending 'modem' (55540 KB)...

OKAY [ 1.807s]

writing 'modem'...

OKAY [ 1.364s]

finished. total time: 3.174s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase modemst1

(bootloader) has-slot:modemst1: not found

erasing 'modemst1'...

OKAY [ 0.018s]

finished. total time: 0.019s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase modemst2

(bootloader) has-slot:modemst2: not found

erasing 'modemst2'...

OKAY [ 0.016s]

finished. total time: 0.018s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot flash fsg fsg.mbn

(bootloader) has-slot:fsg: not found

target reported max download size of 268435456 bytes

sending 'fsg' (1527 KB)...

OKAY [ 0.055s]

writing 'fsg'...

OKAY [ 0.063s]

finished. total time: 0.121s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase cache

(bootloader) has-slot:cache: not found

erasing 'cache'...

OKAY [ 0.017s]

finished. total time: 0.019s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase userdata

(bootloader) has-slot:userdata: not found

erasing 'userdata'...

OKAY [ 0.044s]

finished. total time: 0.046s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot erase customize

(bootloader) has-slot:customize: not found

erasing 'customize'...

(bootloader) Invalid partition name customize

FAILED (remote failure)

finished. total time: 0.014s

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot oem fb_mode_clear

...

OKAY [ 0.006s]

finished. total time: 0.008s

C:\Program Files (x86)\Minimal ADB and Fastboot>reboot

'reboot' is not recognized as an internal or external command,

operable program or batch file.

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot reboot

rebooting...

finished. total time: 0.013s

C:\Program Files (x86)\Minimal ADB and Fastboot>

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