diff --git a/The-Upgrade-Guide.md b/The-Upgrade-Guide.md
index cf954e3..ba73fe0 100644
--- a/The-Upgrade-Guide.md
+++ b/The-Upgrade-Guide.md
@@ -83,6 +83,10 @@ After reset, when it asks you about default launcher, use `DigitalPaperApp`.
 
 Re-do [the launcher mod](https://github.com/HappyZ/dpt-tools/wiki/Suggested-Launcher-Mod). It happened because even though system partition is changed, data partition remained untouched (so do ExtMgr.db and ExtMgr.db-journal). Since I added the launcher mod to the system, to solve the crash, you need to overwrite `ExtMgr.db` and `ExtMgr.db-journal` as suggested in [the launcher mod](https://github.com/HappyZ/dpt-tools/wiki/Suggested-Launcher-Mod).
 
+## Not connect to Wifi but AppLauncher crashes
+
+If AppLauncher crashes but your DPT isn't connected to Wifi (so dpt-tools.py regular fw method can't work), you can directly enter diagnosis mode using a cable via `python dpt-tools.py --diagnosis`. Then use `install-pkg` to install related PKGs.
+
 ## Changing pen color does not work
 
 Or equivalently the setting of pen color is empty. To solve this, you have to reset the device by going to "System Settings" and then "Initialize DPT". Before doing so, back up your documents.