[Fire HD 8 and HD 10 Original Android Development] PaperLawyer:
My Fire HD8 was also on 5.3.7.0 and tonight I bit the bullet to follow the Airton's lead....only to end up with a seemingly bricked Fire. I read this message so many times:

ubuntu@ubuntu:~/Desktop/amonet/amonet-douglas-v1.2/amonet$ sudo ./bootrom-step.sh

[2020-02-12 21:49:47.990949] Waiting for bootrom

[2020-02-12 21:50:44.295428] Found port = /dev/ttyACM0

[2020-02-12 21:50:44.295911] Handshake

* * * If you have a short attached, remove it now * * *

* * * Press Enter to continue * * *

Traceback (most recent call last):

File "/usr/lib/python3/dist-packages/serial/serialposix.py", line 537, in write

n = os.write(self.fd, d)

OSError: [Errno 5] Input/output error

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

File "main.py", line 256, in <module>

main()

File "main.py", line 129, in main

load_payload(dev, "../brom-payload/build/payload.bin")

File "/home/ubuntu/Desktop/amonet/amonet-douglas-v1.2/amonet/modules/load_payload.py", line 123, in load_payload

dev.write32(0x10007008, 0x1971) # low-level watchdog kick

File "/home/ubuntu/Desktop/amonet/amonet-douglas-v1.2/amonet/modules/common.py", line 154, in write32

self.dev.write(b'\xd4')

File "/usr/lib/python3/dist-packages/serial/serialposix.py", line 571, in write

raise SerialException('write failed: {}'.format(e))

serial.serialutil.SerialException: write failed: [Errno 5] Input/output error

However, admiring the persistence of many on this thread (thank you!), I changed the usb cable, power cycled many times and eventually....

ubuntu@ubuntu:~/Desktop/amonet/amonet-douglas-v1.2/amonet$ sudo ./bootrom-step.sh

[2020-02-12 22:05:06.320248] Waiting for bootrom

[2020-02-12 22:09:05.717230] Found port = /dev/ttyACM0

[2020-02-12 22:09:05.718175] Handshake

* * * If you have a short attached, remove it now * * *

* * * Press Enter to continue * * *

[2020-02-12 22:09:10.731213] Init crypto engine

[2020-02-12 22:09:10.755011] Disable caches

[2020-02-12 22:09:10.755663] Disable bootrom range checks

[2020-02-12 22:09:10.775470] Load payload from ../brom-payload/build/payload.bin = 0x4888 bytes

[2020-02-12 22:09:10.778440] Send payload

[2020-02-12 22:09:11.490491] Let's rock

[2020-02-12 22:09:11.491202] Wait for the payload to come online...

[2020-02-12 22:09:12.211554] all good

[2020-02-12 22:09:12.212344] Check GPT

[2020-02-12 22:09:12.589804]

[2020-02-12 22:09:12.590074] Sector size (logical): 512 bytes

[2020-02-12 22:09:12.590288] Disk identifier (GUID): 88C350DB-9F18-49B6-8E03-A4C14049C4EB

[2020-02-12 22:09:12.590439] Partition table holds up to 128 entries

[2020-02-12 22:09:12.590580] This partition table begins at sector 2 and ends at sector 33

[2020-02-12 22:09:12.590703] First usable sector is 34, last usable sector is 30535646

[2020-02-12 22:09:12.590823] Other partition table is at sector 30535679

[2020-02-12 22:09:12.590936]

[2020-02-12 22:09:12.591140] Number Start (sector) End (sector) Size Name

[2020-02-12 22:09:12.594459] 1 1024 7167 3.00 MiB proinfo

[2020-02-12 22:09:12.594696] 2 7168 16383 4.50 MiB PMT

[2020-02-12 22:09:12.594895] 3 16384 17407 512.00 KiB lk

[2020-02-12 22:09:12.595057] 4 17408 18431 512.00 KiB lk2

[2020-02-12 22:09:12.595229] 5 18432 51199 16.00 MiB boot

[2020-02-12 22:09:12.595387] 6 51200 86015 17.00 MiB recovery

[2020-02-12 22:09:12.595574] 7 86016 96255 5.00 MiB tee1

[2020-02-12 22:09:12.595861] 8 96256 106495 5.00 MiB tee2

[2020-02-12 22:09:12.596128] 9 106496 187391 39.50 MiB metadata

[2020-02-12 22:09:12.596380] 10 187392 189439 1024.00 KiB kb

[2020-02-12 22:09:12.596556] 11 189440 191487 1024.00 KiB dkb

[2020-02-12 22:09:12.596746] 12 191488 192511 512.00 KiB MISC

[2020-02-12 22:09:12.596877] 13 192512 208895 8.00 MiB reserved

[2020-02-12 22:09:12.596994] 14 208896 3515391 1.58 GiB system

[2020-02-12 22:09:12.597110] 15 3515392 4383743 424.00 MiB cache

[2020-02-12 22:09:12.597230] 16 4383744 30535646 12.47 GiB userdata

[2020-02-12 22:09:12.604460]

[2020-02-12 22:09:12.604599] Modify GPT

[2020-02-12 22:09:12.604804] Validate GPT

[2020-02-12 22:09:12.605098]

[2020-02-12 22:09:12.605169] Sector size (logical): 512 bytes

[2020-02-12 22:09:12.605210] Disk identifier (GUID): 88C350DB-9F18-49B6-8E03-A4C14049C4EB

[2020-02-12 22:09:12.605256] Partition table holds up to 128 entries

[2020-02-12 22:09:12.605300] This partition table begins at sector 2 and ends at sector 33

[2020-02-12 22:09:12.605327] First usable sector is 34, last usable sector is 30535646

[2020-02-12 22:09:12.605353] Other partition table is at sector 30535679

[2020-02-12 22:09:12.605379]

[2020-02-12 22:09:12.605424] Number Start (sector) End (sector) Size Name

[2020-02-12 22:09:12.605542] 1 1024 7167 3.00 MiB proinfo

[2020-02-12 22:09:12.605659] 2 7168 16383 4.50 MiB PMT

[2020-02-12 22:09:12.605774] 3 16384 17407 512.00 KiB lk

[2020-02-12 22:09:12.605905] 4 17408 18431 512.00 KiB lk2

[2020-02-12 22:09:12.606017] 5 18432 51199 16.00 MiB boot_x

[2020-02-12 22:09:12.606129] 6 51200 86015 17.00 MiB recovery_x

[2020-02-12 22:09:12.606238] 7 86016 96255 5.00 MiB tee1

[2020-02-12 22:09:12.606386] 8 96256 106495 5.00 MiB tee2

[2020-02-12 22:09:12.606521] 9 106496 187391 39.50 MiB metadata

[2020-02-12 22:09:12.606642] 10 187392 189439 1024.00 KiB kb

[2020-02-12 22:09:12.606787] 11 189440 191487 1024.00 KiB dkb

[2020-02-12 22:09:12.606930] 12 191488 192511 512.00 KiB MISC

[2020-02-12 22:09:12.607065] 13 192512 208895 8.00 MiB reserved

[2020-02-12 22:09:12.607187] 14 208896 3515391 1.58 GiB system

[2020-02-12 22:09:12.607321] 15 3515392 4383743 424.00 MiB cache

[2020-02-12 22:09:12.607550] 16 4383744 30084095 12.25 GiB userdata

[2020-02-12 22:09:12.607669] 17 30084096 30309375 110.00 MiB boot

[2020-02-12 22:09:12.607784] 18 30309376 30534655 110.00 MiB recovery

[2020-02-12 22:09:12.613562]

[2020-02-12 22:09:12.613625] Flash new primary GPT

[34 / 34]

[2020-02-12 22:09:13.345656] Flash new backup GPT

[33 / 33]

[2020-02-12 22:09:14.191883]

[2020-02-12 22:09:14.192158] Sector size (logical): 512 bytes

[2020-02-12 22:09:14.192362] Disk identifier (GUID): 88C350DB-9F18-49B6-8E03-A4C14049C4EB

[2020-02-12 22:09:14.192512] Partition table holds up to 128 entries

[2020-02-12 22:09:14.192647] This partition table begins at sector 2 and ends at sector 33

[2020-02-12 22:09:14.192809] First usable sector is 34, last usable sector is 30535646

[2020-02-12 22:09:14.192936] Other partition table is at sector 30535679

[2020-02-12 22:09:14.193054]

[2020-02-12 22:09:14.193255] Number Start (sector) End (sector) Size Name

[2020-02-12 22:09:14.193830] 1 1024 7167 3.00 MiB proinfo

[2020-02-12 22:09:14.194381] 2 7168 16383 4.50 MiB PMT

[2020-02-12 22:09:14.194915] 3 16384 17407 512.00 KiB lk

[2020-02-12 22:09:14.195927] 4 17408 18431 512.00 KiB lk2

[2020-02-12 22:09:14.196493] 5 18432 51199 16.00 MiB boot_x

[2020-02-12 22:09:14.196665] 6 51200 86015 17.00 MiB recovery_x

[2020-02-12 22:09:14.196839] 7 86016 96255 5.00 MiB tee1

[2020-02-12 22:09:14.196955] 8 96256 106495 5.00 MiB tee2

[2020-02-12 22:09:14.197097] 9 106496 187391 39.50 MiB metadata

[2020-02-12 22:09:14.197250] 10 187392 189439 1024.00 KiB kb

[2020-02-12 22:09:14.197400] 11 189440 191487 1024.00 KiB dkb

[2020-02-12 22:09:14.197536] 12 191488 192511 512.00 KiB MISC

[2020-02-12 22:09:14.197660] 13 192512 208895 8.00 MiB reserved

[2020-02-12 22:09:14.197785] 14 208896 3515391 1.58 GiB system

[2020-02-12 22:09:14.197910] 15 3515392 4383743 424.00 MiB cache

[2020-02-12 22:09:14.198034] 16 4383744 30084095 12.25 GiB userdata

[2020-02-12 22:09:14.198343] 17 30084096 30309375 110.00 MiB boot

[2020-02-12 22:09:14.198479] 18 30309376 30534655 110.00 MiB recovery

[2020-02-12 22:09:14.205036]

[2020-02-12 22:09:14.205158] Check boot0

[2020-02-12 22:09:14.447244] Check rpmb

[2020-02-12 22:09:14.657107] Clear preloader header

[8 / 8]

[2020-02-12 22:09:15.072148] Downgrade rpmb

[2020-02-12 22:09:15.075323] Recheck rpmb

[2020-02-12 22:09:15.969810] rpmb downgrade ok

[2020-02-12 22:09:15.971635] Flash preloader

[272 / 272]

[272 / 272]

[2020-02-12 22:09:27.949635] Flash tz

[6459 / 6459]

[2020-02-12 22:11:47.363617] Flash lk

[950 / 950]

[2020-02-12 22:12:08.097616] Inject payload

[8 / 8]

[962 / 962]

[8 / 8]

[962 / 962]

[2020-02-12 22:12:50.398512] Force fastboot

[2020-02-12 22:12:50.706969] Flash preloader header

[4 / 4]

[4 / 4]

[2020-02-12 22:12:51.124317] Reboot