Can you unbrick an iPhone 4S?

I was wondering, if i upgraded my iphone 4S to ios 7 Beta 3 without a developers account with a mirror link stuff, and for some reason i get the message saying my phone is not registered, (and it is put in an unusable state) can i fix that? Is it possible to put my phone in DFU mode and just downgrade back to ios 6.1.3 stock firmware? Or does that not work

please only respond if you know what your talking about

Yes you can.

Follow the following link, its the same as unjailbreaking. I did it, worked fine.
http://theunlockr.com/2013/06/12/how-to-unjailbreak-your-iphone-video/

You can't downgrade.
get a $99 dev account or wait til ios 7 is offically released in a few weeks.
if your in PA, email me i have a few iphone for sale or trade.

4S owner here. It's not possible to downgrade to 6.1.3, which makes running iOS 7 without a UDID registration very dangerous, even if you don't update to newer betas. At any time, Apple can see that your device is not registered and brick it. You should get your UDID registered on a site like http://www.instantudid.com/. I did mine there and I've had no problems with activation or updates.