Can I get back to root-able HBoot version by doing a factory reset

I have a HTC Wildfire (Buzz) that originally came with Eclair. I now have Froyo on it and the Unrevoked tool doesn't work as the HBoot version is not supported (too new for Unrevoked). At this point, I don't care about losing the data on the phone (they are backed up anyway). So, can I do a factory reset to get the old firmware back that can be rooted? I'm ready to do anything to get Cyongenmod on this :)