I was rooted running .605 i mistakenly flashed the 4.5.621 SBF file. it is now not loading anything after bootup except the notification screen. is there any way to fix this?
Did you do a factory reset in stock recovery after the sbf? If not, then power down the phone, hold the power and home key until the phone powers up, then press both the up and down volume keys until a menu appears. Use the volume key to navigate to factory reset and use the power button to select.
From the triangle screen you have to press both volume buttons, this will get you into the actual recovery. From there do a factory reset using the volume buttons to navigate and the power button to confirm.