I also had a 4th gen touch that became a "brick" and was unable to restore and even after the genius bar examined it they declared it "unrecoverable" but my persistance paid off and I was able to finally figure out how to restore it.
This worked for mine, I don't guarantee it will work for yours but if you have gone through the restoration process only to find itunes is stuck on "waiting for ipod" and your touch shows the apple logo with the status bar is empty below it try this: Press and hold ONLY THE POWER BUTTON (the button on the edge of the ipod) and DO NOT LET GO. If yours is like mine it will then start the process of restoration with the status bar filling, then it will verify the restore, then it will update the firmware. LET ME MAKE THIS CLEAR - DO NOT RELEASE THE POWER BUTTON DURING THIS ENTIRE PROCESS - it will take several minutes and your finger will get tired but do not let go!
Once it is done installing the firmware there will be a popup from itunes saying your ipod will restart and appear in itunes. When you see this you can now release the power button and itunes will restart and ask you about the final process of either restoring previous settings or starting with a "clean restore". I don't think it matters which you choose but I chose to restore my old settings and it did work, and then my ipod touch worked just like before!
If this works for you too please reply to this post so others will know mine wasn't just a fluke. It took me 2 weeks of trying all sorts of iterations of pushing buttons and releasing them at various times to get it to work, but finally this was the ONLY way I could find to get mine to complete the restore process!
Good Luck!