Actually, there is an easier way…be sure to be using IPAD charger only.
Get your unit into DFU mode ( easy to find procedure- no need to list it here.
Once its in DFU mode, be sure to leave plugged in and do not touch ipad.
It will stay in DFU mode for about 10 minutes and then since no action has been taken, unit will reboot normally and you should have about 6% power, proceed to normal shutdown and let unit charge for at least 1 hour.
Your welcome