Applied new MIUI Lockscreen, Won't Unlock Now

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http://forum.xda-developers.com – I'm using MIUIAndroid 2.8.3. I got tired of a custom lockscreen, so I put on the stock one. In my haste, I hit the lock button maybe too early while it was still applying. So I locked it, but when I tried to unlock, the screen stayed blank, but the capacitive buttons lighted up. I tried to hit volume up and the back button at the same time, but it doesn't unlock. But what matters is all I really want is to back up my SMS messages. I haven't backed them up for a week maybe, but I have some I'd like to spare. Can I back them up, access them from ADB, or am I out of luck here? (HowTos)