Ok, so I'm having the same problem with my phone. I did the genius bar thing today, and they told me the same thing. However, since this hadn't been posted on here yet, I'll go ahead and add it. My genius guy figured out that if you use the accessibility option (settings>general>accessibility>assistive touch>on) you'll get a touch button that will appear on your screen at all times. Slightly annoying, but you can move it around so it's out of your way. It has several commands, if you tap it, and then hit "device" there's a "lock screen" option. This also works to shut the phone off by pressing and holding. However, to turn your phone back on, you'll have to plug it in. Hope this helps someone!