The back cover and keyboard thing are for the Kindle 1, not the Kindle 2. The Kindle 2 can only be reset, if it's not on, by the power switch.
You must *unplug* the Kindle 2 first. You don't want it connected to the USB port either. Then slide and hold the switch for 20 seconds or so and then release. Set the Kindle 2 down and wait a few minutes to see if it does anything.
If that doesn't work, then it could be your battery is totally drained. Plug the Kindle into the wall for an hour and let it recharge. Then unplug it and do the procedure outlined above again.
If it still won't come on, contact Kindle Support; tell them the steps you've been through and they'll send you a new one.