How do I get my iPhone out of Recovery mode?

My sister's iPhone is stuck in Recovery mode. She plugged it into her computer and it started to update software. Upon doing this, it gave a message saying "Could not restore iPhone, an unknown error occurred (1603)". She did not unplug it while it was syncing. Now, it is stuck on the Recovery mode screen with a USB cable pointing to the iTunes logo. We tried putting the device into DFU mode, but this didn't help. Please give us as detailed instructions as possible. Thanks!|||Hold power for 10 seconds...keep holding power and start holding home for 15 sec then let go of home and keep holding power.... Not duf mode...