iPhone problem with restoring firmware
I have updated my iPhone 3gs firmware from 4.1 to 4.2.1. The problem is I didn't know my iPhone is with new bootroom(I thought it's with the old one). During the upgrade the redsnow told me I am with new bootroom so I have started from the beginning. Meantime, it appeared the logo and the loading bar.I thought something went wrong so I tried to restore it with iTunes. It appeared an error.As I know now, I was supposed to upgrade with custom firmware, not iTunes. Now I don't know what to do, I can't restore to 4.2.1 because my iPhone can't be turned off and connected to the PC in the same time. Please tell me what to do, should I have to go to service.
Thanks in advance, bggashnik