Debugging system hangs

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?
  • If possible, please attach an external monitor and check if the external monitor works.
• 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. The VolumeUp key here is the key in the top row on the keyboard and not the side button.
    • 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 within 20 seconds from first 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.