I freaked out this morning when my S7 crashed. While playing a podcast, the audio kept running, but the LED went red. The screen stayed black, the Home button would cause the capacitive touch buttons to light. But otherwise, it was unresponsive. I held down the power button for 20 seconds, nothing happened. The trick is to hold Volume Down + Power buttons and you can get to the maintenance boot screen where you can reboot or power down.
This apparently is a common issue: http://forums.androidcentral.com/samsung-galaxy-s7/652111-unresponsive-black-screen-2.html
I searched here in the vzw forum and couldn't find a post on this..hope this isn't a duplicate report.
Anyone else have this problem? This was an alarming thing to have happen and seems like a serious bug.