Why my tablet keeps on restarting after few seconds?

My Samsung Galaxy Tab 2 10.1 keeps on restarting by itself after few seconds. It stays on for a few seconds but again turns off to restart. It happened while I was downloading some apps using wi-fi. When it is on, i tried to uninstall the downloaded apps but the apps like lock-it, hi security, and device policy couldn't be uninstalled.Can anybody help me?

Welcome to Android Central! Does this persist in Safe Mode as well? https://support.t-mobile.com/docs/DOC-18895