Thinking about going Root and flashing

[hellbringer616]

okay, rand into a snag, I rooted my phone, But i guess to flash to the 2.2 ROM i need an updated radio (according to a guide i found here http://www.jonamerica.com/technology...yo-2-2-update/ ) So it told me to unroot, and here is where i am stuck. downloaded the file they told me to. And put it in my SD card, and now where it says reboot to the bootloader it wont load the file. downloaded 3 times.

using the unrEVOked utility (clockworkmod i think) and trying that way it says
"E:Can't open /sdcard/p31img.zip
(bad)"