There’s a cool feature where from a totally powered off Android device it can boot up when a power source is connected to it. It requires root and also running a configuration command. This worked on my Nexus 7 2013 model so your mileage may vary.
Reboot into recovery mode with the device attached via USB:
adb reboot bootloader
Turn on the feature:
fastboot oem off-mode-charge 0
To undo this setting go through the steps above but use this command to turn it off:
fastboot oem off-mode-charge 1
A pretty cool feature especially for embedded projects.