Chromebook CB315-3H won't startup without the AC adapter being plugged in.

Please try powering off and seeing if a quick Hardware Reset helps.
To fix some Chromebook problems, you might need to reset your Chromebook hardware, also called a hard reset.

Try a hard reset only after other ways to fix the problem have failed. It will restart your Chromebook hardware (like your keyboard and touchpad), and might delete some files in your Downloads folder.

Hard reset your Chromebook
For most Chromebooks, follow the steps below:

Turn off your Chromebook.
Press and hold Refresh and tap Power .
When your Chromebook starts up, release Refresh .
Tips:

You can also press and hold Back + Refresh + Power for at least 10 seconds.
On tablets: Press and hold the Volume Up and Power buttons for at least 10 seconds, then release them.
Other ways to hard reset
For some Chromebooks, you reset the hardware by pressing a special reset button, unplugging the power cable, or removing and re-inserting the battery. If you see your device in this list, follow the steps to reset its hardware.

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