Debugging system hangs (go/cros-debug-hang)

If your Chromebook appears hung (i.e. the screen is frozen and the keyboard and/or trackpad are unresponsive), try the following steps:
  • Pre-Recovery Steps
    • Note any visible system indicators like LEDs.  Are they blinking or solid.  What color?
    • Note charging/discharging behavior if possible.  Does plugging a charger in change LED.
    • Note USB response.  Does touching an gnubby blink.  Does charging a phone via a USB port work?
  • Recovery Steps
    • Press Alt+VolumeUp+X. If you're using a Chromebox, use F10 instead of VolumeUp. These three keys need to be pressed in that order. 
      • This should cause the Chrome browser to restart, and it may take a few seconds.  If the system becomes responsive, go to last step.
    • Press Alt+VolumeUp+X a second time. 
      • This should cause the kernel to panic-reboot. If the system becomes responsive, go to last step.
    • Press Alt+VolumeUp+R which should cause a warm reset & reboot. If so, go to last step. (This may not work on older hardware.)
    • Press and hold the power button for 8+ seconds and the system will power off (if shutdown is clean) or it will reboot via EC reset
    • Press Refresh+Power button(F3).  This causes an EC reset on most systems and should be used only as a last resort as it minimizes the amount of available debug info.
  • Last Step
    • Power on  (if necessary) Log in, and immediately file feedback using Alt+Shift+i. 
      • Make sure that "Send system and app information" is checked.
      • Make sure to identify what recovery steps you used including the ones you believed failed.
You may also be able to see crash report IDs at chrome://crashes.

For a complete and up-to-date list of debug key sequences including those for ChromiumOS devices without a keyboard check here.