Add some content to docs/TROUBLESHOOTING.md (#48)

docs/TROUBLESHOOTING.md

@@ -1,11 +1,44 @@
 # Troubleshooting
 
-**TODO: We don't have a proper troubleshooting guide yet, its best just to ask on the discord, and hopefully we'll update this as time goes on.**
+After an initial reboot an unauthenticated telnet service (port 23) is exposed.
+In case of any issues it can be used for debugging. Additionally, if an error
+occurs during Homebrew Channel install, the bootstrap shell script is removed,
+and the TV should return to original state after a reboot. Then, rooting may be
+reattempted.
 
-- Check if LG Connect Apps is enabled
+## Exploit fails on stage 1 (system browser)
+- Check if LG Connect Apps is enabled (webOS 3.x devices)
 - Verify if http://localhost:3000 works in webOS system browser
-- After an initial reboot an unauthenticated telnet service (port 23) is exposed.
-  In case of any issues it can be used for debugging. Additionally, if an error
-  occurs during Homebrew Channel install, the bootstrap shell script is removed,
-  and the TV should return to original state after a reboot. Then, rooting may be
-  reattempted.
+
+## Exploit fails on stage 2 (full screen app)
+- If the message says "Service does not exist:
+  com.webos.service.downloadmanager" - your TV is running webOS TV version older
+  than 3.4, and thus the service we use a vulnerability in is not present.
+  RootMyTV will not work on your TV, and there's no way of upgrading to a
+  vulnerable version. You may try using some older exploits like
+  [GetMeIn](https://forum.xda-developers.com/t/getmein-one-time-rooting-jailbreaking-tool-for-webos-lg-tvs.3887904/).
+- If the message says "Denied method call", there's a chance LG already patched
+  your TV firmware. In certain cases (when only a system app update has been
+  released, not a full firmware update) you *may try*:
+    * unplugging the TV from the network
+    * doing a "Reset to initial settings", going through the first time wizard
+    * running https://rootmy.tv immediately after reconnecting the network
+- If the message says "This likely means your TV is not vulnerable to LunaDownloadMgr
+  exploit." **and your TV is running webOS TV version between 3.0.0 and 3.4.0** you
+  may try checking if there's a system update available. A vulnerability
+  in LunaDownloadMgr we use has been introduced in webOS 3.4.0 which got
+  released on some TV models.
+
+  **NOTE:** "webOS TV Version" (core system version, formatted
+  `1.2.3-123456 (some-codename)`) is a different thing to
+  "Software Version" (per-model firmware version, formatted `01.23.45`).
+
+## TV reboots but Homebrew Channel is missing
+Your TV is already patched. Wait for another root exploit release.
+
+## Homebrew Channel shows up/telnet works but everything disappears after a reboot
+This may be caused by some leftover files from RootMyTV v1. You can either:
+- Connect over telnet and run: `rm /media/cryptofs/apps/usr/palm/services/com.palmdts.devmode.service/start-devmode.sh`
+- or just run "Reset to Initial Settings" option in webOS settings
+
+Afterwards you will need to run https://rootmy.tv again.