[Fire HD 8 and HD 10 Q&A, Help & Troubleshooting] MontysEvilTwin:
I had assembled a Fire HD 8 (2016) using parts from three different tablets, and I thought I'd have a play and see it if I could unlock it using a modified version of amonet for karnak (Fire HD 8, 2018).

I started with a rooted Fire HD 8 (2016) running Fire OS 5.6.3.4 (build 626536720). Amonet-karnak-v3.01 was downloaded from here: https://xdaforums.com/showpost.php?p=80166353&postcount=1. Image files from Fire OS 5.6.3.4, update-kindle-49.6.2.6_user_626536720.bin: lk.bin, tz.img, preloader.bin, preloader.hdr0 and preloader.hdr1 were copied to amonet/bin, replacing the originals. The script 'fireos-step.sh'' was edited to allow 'max_pl=6' (preloader version 6), to change the model to 'full_giza' and to change the path (PART_PREFIX=) to /dev/block/platform/mtk-msdc.0.

The output from running the modified 'fireos-step.sh' script was as follows:

x@x:~/Downloads/amonet-giza-t/amonet$ sudo ./fireos-step.sh
Testing root access...
uid=0(root) gid=0(root) context=u:r:init:s0

PL version: 6 (6)
LK version: 1 (1)
TZ version: 258 (258)

Flashing PL
1602 KB/s (138924 bytes in 0.084s)
271+1 records in
271+1 records out
138924 bytes transferred in 0.063 secs (2205142 bytes/sec)
271+1 records in
271+1 records out
138924 bytes transferred in 0.016 secs (8682750 bytes/sec)

Flashing LK-payload
62 KB/s (2872 bytes in 0.044s)
5+1 records in
5+1 records out
2872 bytes transferred in 0.005 secs (574400 bytes/sec)

Flashing LK
4234 KB/s (487392 bytes in 0.112s)
951+1 records in
951+1 records out
487392 bytes transferred in 0.045 secs (10830933 bytes/sec)

Flashing TZ
4218 KB/s (3307008 bytes in 0.765s)
6459+0 records in
6459+0 records out
3307008 bytes transferred in 0.287 secs (11522675 bytes/sec)
6459+0 records in
6459+0 records out
3307008 bytes transferred in 0.297 secs (11134707 bytes/sec)

Flashing TWRP
4285 KB/s (13930496 bytes in 3.174s)
27208+0 records in
27208+0 records out
13930496 bytes transferred in 1.046 secs (13317873 bytes/sec)

Patching boot
2+0 records in
2+0 records out
1024 bytes transferred in 0.001 secs (1024000 bytes/sec)
2+0 records in
2+0 records out
1024 bytes transferred in 0.004 secs (256000 bytes/sec)
- Inject microloader
2+0 records in
2+0 records out
1024 bytes transferred in 0.004 secs (256000 bytes/sec)

Flashing PL header
44 KB/s (2048 bytes in 0.044s)
44 KB/s (2048 bytes in 0.044s)
4+0 records in
4+0 records out
2048 bytes transferred in 0.040 secs (51200 bytes/sec)
4+0 records in
4+0 records out
2048 bytes transferred in 0.052 secs (39384 bytes/sec)

Rebooting to TWRP
x@x:~/Downloads/amonet-giza-t/amonet$

This seemed OK but after rebooting, the tablet got stuck on the white Amazon logo, with no recovery mode available.

Amonet_giza_v1.3 was downloaded from here: https://xdaforums.com/showpost.php?p=80232977&postcount=1. I ran the script 'bootrom-step.sh' (shorting method) and this was apparently sucessful:

x@x:~/Downloads/amonet-giza-v1.3$ sudo ./bootrom-step.sh
[2020-06-17 14:49:13.017742] Waiting for bootrom
[2020-06-17 14:49:44.205417] Found port = /dev/ttyACM0
[2020-06-17 14:49:44.215424] Handshake
[2020-06-17 14:49:44.263501] Disable watchdog

* * * Remove the short and press Enter * * *

[2020-06-17 14:49:48.644612] Init crypto engine
[2020-06-17 14:49:48.790589] Disable caches
[2020-06-17 14:49:48.798307] Disable bootrom range checks
[2020-06-17 14:49:48.898946] Load payload from ../brom-payload/build/payload.bin = 0x48D8 bytes
[2020-06-17 14:49:48.965959] Send payload
[2020-06-17 14:49:53.690455] Let's rock
[2020-06-17 14:49:53.699383] Wait for the payload to come online...
[2020-06-17 14:49:54.420378] all good
[2020-06-17 14:49:54.429345] Check GPT
[2020-06-17 14:49:54.802163] gpt_parsed = {'nvram': (7168, 10240), 'recovery': (92416, 32768), 'expdb': (154880, 20480), 'para': (137472, 1024), 'lk': (58880, 1000), 'secro': (125184, 12288), 'frp': (175360, 2048), 'protect2': (37888, 20480), 'metadata': (197888, 80640), 'logo': (138496, 16384), 'tee1': (177408, 10240), 'protect1': (17408, 20480), 'tee2': (187648, 10240), 'seccfg': (58368, 512), 'boot': (59880, 32536), 'proinfo': (1024, 6144)}
[2020-06-17 14:49:54.806253] Check boot0
[2020-06-17 14:49:55.053280] Check rpmb
[2020-06-17 14:49:55.269372] Downgrade rpmb
[2020-06-17 14:49:55.277150] Recheck rpmb
[2020-06-17 14:49:56.174262] rpmb downgrade ok
[2020-06-17 14:49:56.180584] Clear preloader header
[8 / 8]
[2020-06-17 14:49:56.897490] Flashing TZ
[6459 / 6459]
[2020-06-17 14:52:29.248010] Flash LK
[952 / 952]
[2020-06-17 14:52:52.133657] Flash PL
[280 / 280]
[2020-06-17 14:53:10.364218] Reboot
x@x:~/Downloads/amonet-giza-v1.3

However, it is still getting stuck at the white Amazon logo. Is there any way of resurrecting this tablet?