[Fire HD 8 and HD 10 Original Android Development] Cobraroja:
Hi, same problem here, after short TP28, bootrom-step.sh finishes "successfully" but still in Preloader.

[2019-10-15 09:31:28.148013] Waiting for bootrom

[2019-10-15 09:31:39.698884] Found port = /dev/ttyACM0

[2019-10-15 09:31:39.699227] Handshake

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

* * * Press Enter to continue * * *

[2019-10-15 09:31:41.702987] Init crypto engine

[2019-10-15 09:31:41.718476] Disable caches

[2019-10-15 09:31:41.719057] Disable bootrom range checks

[2019-10-15 09:31:41.731175] Load payload from ../brom-payload/build/payload.bin = 0x4888 bytes

[2019-10-15 09:31:41.735226] Send payload

[2019-10-15 09:31:42.278686] Let's rock

[2019-10-15 09:31:42.279416] Wait for the payload to come online...

[2019-10-15 09:31:43.418109] all good

[2019-10-15 09:31:43.418816] Check GPT

[2019-10-15 09:31:43.797265]

[2019-10-15 09:31:43.797527] Sector size (logical): 512 bytes

[2019-10-15 09:31:43.797775] Disk identifier (GUID): 6679D4EB-2287-4373-B34B-34015A123D2A

[2019-10-15 09:31:43.797959] Partition table holds up to 128 entries

[2019-10-15 09:31:43.798119] This partition table begins at sector 2 and ends at sector 33

[2019-10-15 09:31:43.798264] First usable sector is 34, last usable sector is 30777310

[2019-10-15 09:31:43.798401] Other partition table is at sector 30777343

[2019-10-15 09:31:43.798534]

[2019-10-15 09:31:43.798744] Number Start (sector) End (sector) Size Name

[2019-10-15 09:31:43.800788] 1 1024 7167 3.00 MiB proinfo

[2019-10-15 09:31:43.801383] 2 7168 16383 4.50 MiB PMT

[2019-10-15 09:31:43.801905] 3 16384 17407 512.00 KiB lk

[2019-10-15 09:31:43.802501] 4 17408 18431 512.00 KiB lk2

[2019-10-15 09:31:43.803011] 5 18432 51199 16.00 MiB boot_x

[2019-10-15 09:31:43.803464] 6 51200 86015 17.00 MiB recovery_x

[2019-10-15 09:31:43.803914] 7 86016 96255 5.00 MiB tee1

[2019-10-15 09:31:43.804430] 8 96256 106495 5.00 MiB tee2

[2019-10-15 09:31:43.804878] 9 106496 187391 39.50 MiB metadata

[2019-10-15 09:31:43.805320] 10 187392 189439 1024.00 KiB kb

[2019-10-15 09:31:43.805762] 11 189440 191487 1024.00 KiB dkb

[2019-10-15 09:31:43.806201] 12 191488 192511 512.00 KiB MISC

[2019-10-15 09:31:43.806642] 13 192512 208895 8.00 MiB reserved

[2019-10-15 09:31:43.807085] 14 208896 3515391 1.58 GiB system

[2019-10-15 09:31:43.807536] 15 3515392 4383743 424.00 MiB cache

[2019-10-15 09:31:43.807988] 16 4383744 30325759 12.37 GiB userdata

[2019-10-15 09:31:43.808585] 17 30325760 30551039 110.00 MiB boot

[2019-10-15 09:31:43.809427] 18 30551040 30776319 110.00 MiB recovery

[2019-10-15 09:31:43.850469]

[2019-10-15 09:31:43.850686] Check boot0

[2019-10-15 09:31:44.092181] Check rpmb

[2019-10-15 09:31:44.302167] Clear preloader header

[8 / 8]

[2019-10-15 09:31:44.716023] Downgrade rpmb

[2019-10-15 09:31:44.718014] Recheck rpmb

[2019-10-15 09:31:45.612636] rpmb downgrade ok

[2019-10-15 09:31:45.613285] Flash tz

[6459 / 6459]

[2019-10-15 09:34:04.345394] Flash lk

[950 / 950]

[2019-10-15 09:34:24.957983] Inject payload

[1 / 1]

[962 / 962]

[1 / 1]

[962 / 962]

[2019-10-15 09:35:06.711893] Force fastboot

[2019-10-15 09:35:07.021108] Flash preloader

[280 / 280]

[272 / 272]

[2019-10-15 09:35:19.394220] Reboot to unlocked fastboot

Device doesn't reboot nor recognized by fastboot (stuck on waiting device). Turning on the tablet, bootloop in Amazon logo, also recovery is missing (not entering using keycomb, I executed step1 and step2 but tablet started to bootloop in Amazon logo then tried bootrom-step.sh without success).