The battery completely drained and now I have it plugged in to the computer via a usb cord but I am not sure it is charging at all. How can I tell?

Hello

Just follow these steps to fix this issue:

1. Plug the device into the Kindle A/C adapter (not your computer) and let it charge for a few hours. Be sure the charging light is lit -- sometimes a drained Kindle will stop charging a few seconds after you plug it in. Unplug and replug until the light stays on steadily, then leave it alone. Most of the time you'll come back to a restored kindle. If not, go on to step 2.
2. If you still see the same Critical Battery screen after charging, unplug the USB cord, then hold the power slide to the right for at least 20 seconds.
3. Release the power slide, then immediately press and hold the Home key for another 30 - 45 seconds.
4. Once the Kindle's screen begins to flash, release the Home key. The eReader will boot to recovery mode. To continue, press and hold the R key until the screen flashes again.
5. After the device is finished rebooting, you may see the Critical Battery screen once more. If so, plug in the USB cord and wait for the Kindle to return to the Home screen.

For any help or query visit us: www Kindle Com Support

Did it come with any cables like a USB cable that plugs from PC to Tablet. USB port of P.C should charge tablet when plugged in via USB Port

If the battery isn't too far gone, here's how to revive it: Plug the device into the Kindle A/C adapter (not your computer) and let it charge for a few hours. Be sure the charging light is lit -- sometimes a drained Kindle will stop charging a few seconds after you plug it in. Unplug and replug until the light stays on steadily, then leave it alone. Most of the time you'll come back to a restored Kindle. If not, go on to step 2. If you still see the same Critical Battery screen after charging, unplug the USB cord, then hold the power slide to the right for at least 20 seconds. Release the power slide, then immediately press and hold the Home key for another 30 - 45 seconds. Once the Kindle's screen begins to flash, release the Home key. The eReader will boot to recovery mode. To continue, press and hold the R key until the screen flashes again. After the device is finished rebooting, you may see the Critical Battery screen once more. If so, plug in the USB cord and wait for the Kindle to return to the Home screen. - See more at: http://www.laptopmag.com/articles/kindle-critical-battery-error#sthash.Rtxwp4El.dpuf

How To Restore Your Kindle If It Experiences Critical Battery Error

f you can't get past step 3, the battery might be too far gone. Contact Kindle customer service via phone (866-321-8851) to walk through extra troubleshooting steps. If they can't revive it, Amazon will usually replace the eReader for free. - See more at: http://www.laptopmag.com/articles/kindle-critical-battery-error#sthash.Rtxwp4El.dpuf
How To Restore Your Kindle If It Experiences Critical Battery Error

An adapter should have come with your Kindle Fire HD7 when you purchased it. The USB 2.0 cord is universal, so you could plug it into your computer and charge it that way also (while the computer is on).

I am assuming that you checked to make sure you had all the parts. Included in the Box Fire HD 7 tablet, USB 2.0 cable, 5W power adapter, and Quick Start Guide

Charge it up on the computer

first go to a mobile shop ask hif it it is the problem of battry or some hardware problem inside the tab and also check the charger weather it works or not

Use the original plug what came with the Kindle

Hi It will not charge. Are you sure that the battery is OK? Do you charge the tablet with electricity or via USB? You have checked the cord and wire into the the plug and the plug itself. Is it possible for you to borrow a charger to find out if it is the battery that is not working. All the best Kolbrun

Charge it via the usb socket. Many cell phone chargers will charge them via the mini usb socket