Most of the recent Jailbreaking tools like Sn0wbreeze, Pwnagetool, Redsn0w etc would build a new custom .ipsw file for your device after accepting the original .ipsw file and then converting them to a new one with additional stuff merged in them. These custom .ipsw files would have the Cydia Apps, custom boot logo, homepage wallpapers etc. In most cases you will have to reboot your Apple iPhone into the Restore Mode and then run iTunes to restore the custom previously generated file along with bootrom. Read below for the detailed process.
How To Put The iPhone Into Restore Mode – Run the iTunes Application and Connect your Device to the Computer. Next Press and hold the Home button and the Sleep or Wake button at the same time. Once you find that the screen has gone black you will be into the Restore Mode and you will have to continue hold the Home button till the iTunes displays a message saying ‘iTunes has detected an iPhone in recovery mode. You must restore this iPhone before it can be used with iTunes’.
Next you will have to press the Shift + Restore button to allow iTunes to ask you to select the custom .ipsw file to restore. This is when even after a full restore the Display of the following message from the iPhone screen wont go.
Now download a copy of iReb which is a tool for to Bypass any errors while restoring to a custom IPSW in iTunes compatible for iPhone 2G, iPhone 3G, and iPod Touch 1G.
To run this software you will have to put your iPhone into DFU Mode and then select the device which you are currently using. After a few minutes you will get a white screen following which the ih8sn0w.exe application will crash and if you are on the white screen then everything is normal and working perfectly. Now you can run iTunes and restore the original or custom .ipsw file.