For me it really depends on the device.
A laptop, I would do the normal troubleshooting steps of,
1. Do you have power at your house?
2. Is the laptop plugged into the power brick? the brick into the wall? do you see the charge light near where the plug goes on the laptop?
3. (if both above are yes) Unplug the charger, Hold down the power button for 10 seconds. Plug it back in and try again.
4. Other steps as needed for the model the user has (Some laptops you can still remove the battery for, others you can't etc)
And go from there. Some devices are similar, others not. But you get the idea.