[NiLuJe]

@kapaggar: Huh. I'll try to take a look at it, but I have tremendous issues accessing anything amazon.cn, so that may get tricky...

EDIT: Got it through my build box. I guess my ISP is getting sneaky...

EDIT²: Well, that was easy.

┌─(niluje@tyrande:pts/0)────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────(~)─┐
└─(0.29:32%:22:04:%)── file update-kindle-6.0.3_user_603479820.bin                                                                                                                                                                                          ──(Tue, May 22)─┘
update-kindle-6.0.3_user_603479820.bin: Java archive data (JAR)
┌─(niluje@tyrande:pts/0)────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────(~)─┐
└─(0.27:32%:22:04:%)── unzip -l update-kindle-6.0.3_user_603479820.bin                                                                                                                                                                                      ──(Tue, May 22)─┘
Archive:  update-kindle-6.0.3_user_603479820.bin
signed by SignApk
  Length      Date    Time    Name
---------  ---------- -----   ----
        0  10-20-2016 02:52   system.patch.dat
   124644  10-20-2016 02:52   META-INF/com/amazon/android/check-binary
     1316  10-20-2016 02:52   META-INF/com/amazon/android/target.blocklist
     3945  10-20-2016 02:52   META-INF/com/amazon/android/target.build.prop
       45  10-20-2016 02:52   META-INF/com/amazon/android/target.system.devicepath
      137  10-20-2016 02:52   META-INF/com/amazon/android/target.system.map
       40  10-20-2016 02:52   META-INF/com/amazon/android/target.system.map.sha1
      132  10-20-2016 02:52   META-INF/com/android/metadata
   504416  10-20-2016 02:52   META-INF/com/google/android/update-binary
      860  10-20-2016 02:52   META-INF/com/google/android/updater-script
  5617664  10-20-2016 02:52   boot.img
    16057  10-20-2016 02:52   file_contexts
   524288  10-20-2016 02:52   images/mboot.bin
   123904  10-20-2016 02:52   images/spl.imx
      235  10-20-2016 02:52   ota.prop
419807232  10-20-2016 02:52   system.new.dat
      172  10-20-2016 02:52   system.transfer.list
     3945  10-20-2016 02:52   system/build.prop
     1452  10-20-2016 02:52   META-INF/com/android/otacert
     1609  10-20-2016 02:52   META-INF/MANIFEST.MF
     1833  10-20-2016 02:52   META-INF/CERT.SF
     1553  10-20-2016 02:52   META-INF/CERT.RSA
---------                     -------
426735479                     22 files

EDIT^3: https://github.com/NiLuJe/KindleTool...5c97b514a60451

Beyond that, I'm not familiar with Fire OS, so, meh. ^^.