Root Can't boot after .77 hboot downgrade

Okay so this might sound a little stupid, but I was going to root a replacement phone, but for some reason it starting going into a boot loop, and I couldn't root using unrevoked because it kept getting interrupted, so I thought downgrading to .77 hboot would help, but now the phone won't boot at all, it just boots to hboot everytime. I've read that you have to flash a rom or kernel after the hboot downgrade, but is there any way to do this from hboot/recovery without root or s-off?

At this point, I just need to get the phone to boot so I can get started rooting and transferring my rom over.

Alright well, I used the official 2.2 PB31IMG.zip from here...
http://androidforums.com/incredible-all-things-root/181255-how-downgrade-official-2-2-a.html

And now I got it to boot into official 2.2, but it's still doing the boot loop, is there a fix for this, or should I just call and send the replacement back for a different one?