Major Issues with the iPad 3G
If you are having major issues with the iPad (it won't power on, it constantly locks up, or just strange behavior that nothing else fixes) there are a few steps to try.
Let's take the power issue. If your iPad 3G will not turn on connect it to the charging cable and make sure the cable is connected to a wall charger (not the computer). Connect to the charger and see if it turns on after a minute or two. If it will not turn on and iTunes still sees it when connected to the computer follow the suggestion below.
Locking up and other strange behavior calls for something more drastic. You have to erase and restore your iPad via iTunes. When the iPad is connected to the computer you want to select it in iTunes. On the first tab in iTunes for your iPad you will see a restore button. Click that button and confirm that you want to erase the iPad. If you have your iPad backed up (iTunes does this regularly) you can restore the iPad from the backup without having to reinstall and organize your apps again.
If all of the above fails it is time to call in Apple by phone or by visiting an Apple store/authorized Apple repair center. Hopefully, your iPad will still be under warranty or it is something they can quickly fix without a big charge.
Like I said at the beginning of this article the iPad is great, but it isn't perfect. However, there are ways (like those above) that can help you troubleshoot and possibly fix your iPad 3G problems.