[Nexus 5X Q&A, Help & Troubleshooting] Omseik:
My Nexus 5X was on 7.1.2 and rooted. But I wanted to go to 7.1.1 (for some compatibility).

So, I went on Google APIs and downloaded the 7.1.1 N4F26T, Mar 2017 build and together with Platform Tools I used "flash-all".

But... at a certain point, I get an error and it stopped.

Logs:

C:\Users\*\Desktop\android img\bullhead-n4f26t>flash-all

target reported max download size of 536870912 bytes

sending 'bootloader' (4603 KB)...

OKAY [ 0.173s]

writing 'bootloader'...

OKAY [ 0.135s]

finished. total time: 0.317s

rebooting into bootloader...

OKAY [ 0.020s]

finished. total time: 0.022s

target reported max download size of 536870912 bytes

sending 'radio' (56614 KB)...

OKAY [ 1.359s]

writing 'radio'...

OKAY [ 0.494s]

finished. total time: 1.859s

rebooting into bootloader...

OKAY [ 0.020s]

finished. total time: 0.020s

target reported max download size of 536870912 bytes

archive does not contain 'boot.sig'

archive does not contain 'recovery.sig'

archive does not contain 'system.sig'

archive does not contain 'vendor.sig'

wiping userdata...

Creating filesystem with parameters:

Size: 27283927040

Block size: 4096

Blocks per group: 32768

Inodes per group: 8176

Inode size: 256

Journal blocks: 32768

Label:

Blocks: 6661115

Block groups: 204

Reserved block group size: 1024

Created filesystem with 11/1667904 inodes and 148720/6661115 blocks

wiping cache...

Creating filesystem with parameters:

Size: 100663296

Block size: 4096

Blocks per group: 32768

Inodes per group: 6144

Inode size: 256

Journal blocks: 1024

Label:

Blocks: 24576

Block groups: 1

Reserved block group size: 7

Created filesystem with 11/6144 inodes and 1422/24576 blocks

--------------------------------------------

Bootloader Version...: BHZ11h

Baseband Version.....: M8994F-2.6.36.2.20

Serial Number........: 014702846496c259

--------------------------------------------

checking product...

OKAY [ 0.021s]

checking version-bootloader...

OKAY [ 0.017s]

checking version-baseband...

OKAY [ 0.018s]

sending 'boot' (12013 KB)...

OKAY [ 0.345s]

writing 'boot'...

OKAY [ 0.105s]

sending 'recovery' (16141 KB)...

OKAY [ 0.464s]

writing 'recovery'...

OKAY [ 0.163s]

erasing 'system'...

OKAY [ 0.575s]

sending sparse 'system' 1/6 (520438 KB)...

OKAY [ 13.092s]

writing 'system' 1/6...

OKAY [ 5.904s]

sending sparse 'system' 2/6 (515462 KB)...

OKAY [ 13.286s]

writing 'system' 2/6...

OKAY [ 5.574s]

sending sparse 'system' 3/6 (479562 KB)...

FAILED (data transfer failure (Unknown error))

finished. total time: 53.984s

Press any key to exit...

Ok... the phone is in bootloop (for more than 20 min). I tried again, the same thing. I installed Nexus Root Toolkit 2.1.6 and I tried with "Flash Stock + Unroot" with the same build N4F26T but I get the same thing.

So, I tried an older build, N4F26O.

This one worked, kind of, some errors in the process but it managed to finish the flashing.

Logs:

Flash Stock + Unroot [WugFresh Development]

------------------------------------------------------------------

target reported max download size of 536870912 bytes

sending 'bootloader' (4603 KB)...

OKAY [ 0.182s]

writing 'bootloader'...

OKAY [ 0.133s]

finished. total time: 0.320s

rebooting into bootloader...

OKAY [ 0.011s]

finished. total time: 0.013s

target reported max download size of 536870912 bytes

sending 'radio' (56614 KB)...

OKAY [ 1.404s]

writing 'radio'...

OKAY [ 0.491s]

finished. total time: 1.902s

rebooting into bootloader...

OKAY [ 0.010s]

finished. total time: 0.012s

target reported max download size of 536870912 bytes

erasing 'vendor'...

OKAY [ 0.076s]

sending 'vendor' (25792 KB)...

OKAY [ 0.676s]

writing 'vendor'...

FAILED (remote: buffer overreads occured due to invalid sparse header)

finished. total time: 0.958s

target reported max download size of 536870912 bytes

erasing 'system'...

OKAY [ 0.568s]

sending sparse 'system' 1/6 (520382 KB)...

OKAY [ 12.999s]

writing 'system' 1/6...

OKAY [ 5.097s]

sending sparse 'system' 2/6 (515518 KB)...

OKAY [ 12.752s]

writing 'system' 2/6...

OKAY [ 5.570s]

sending sparse 'system' 3/6 (479542 KB)...

OKAY [ 11.994s]

writing 'system' 3/6...

OKAY [ 4.906s]

sending sparse 'system' 4/6 (514681 KB)...

OKAY [ 13.001s]

writing 'system' 4/6...

OKAY [ 5.170s]

sending sparse 'system' 5/6 (524285 KB)...

OKAY [ 13.645s]

writing 'system' 5/6...

OKAY [ 5.062s]

sending sparse 'system' 6/6 (182573 KB)...

OKAY [ 4.856s]

writing 'system' 6/6...

OKAY [ 1.688s]

finished. total time: 97.350s

Creating filesystem with parameters:

Size: 27283927040

Block size: 4096

Blocks per group: 32768

Inodes per group: 8176

Inode size: 256

Journal blocks: 32768

Label:

Blocks: 6661115

Block groups: 204

Reserved block group size: 1024

Created filesystem with 11/1667904 inodes and 148720/6661115 blocks

target reported max download size of 536870912 bytes

erasing 'userdata'...

OKAY [ 0.611s]

sending 'userdata' (138993 KB)...

OKAY [ 3.435s]

writing 'userdata'...

OKAY [ 1.534s]

finished. total time: 5.581s

Creating filesystem with parameters:

Size: 100663296

Block size: 4096

Blocks per group: 32768

Inodes per group: 6144

Inode size: 256

Journal blocks: 1024

Label:

Blocks: 24576

Block groups: 1

Reserved block group size: 7

Created filesystem with 11/6144 inodes and 1422/24576 blocks

target reported max download size of 536870912 bytes

erasing 'cache'...

OKAY [ 0.073s]

sending 'cache' (5688 KB)...

OKAY [ 0.231s]

writing 'cache'...

OKAY [ 0.068s]

finished. total time: 0.371s

rebooting...

finished. total time: 0.012s

Still in bootloop after 20 min, so I tried what the NRT said, went into recovery and did a factory reset from there, but same ****. After 20 minutes still in bootloop.

Tried the Soft-Bricked/Bootloop in NRT but it didn't help.

I don't really know what to do....

Send help