You know, I post this so often, I'm thinking about just making it my signature.....
Anyway, you need to force the Pre into novacom USB mode and run the WebOSDr.
I'm assuming you know how to install novacom drivers on your desktop, or you probably wouldn't have been able to brick your Pre. So, assuming you've been able to run things like novaterm and/or WebOSQuickInstall, just do the following:
1) Turn your Pre completely off. If it's so messed up that you can't turn it off, remove the battery to kill it. If you have to take the battery out, leave it out until I tell you to put it back it.
2) Plug your Pre into the USB port on your computer.
3) Press and hold the volume up button. Do NOT let go of the volume up button until I tell you to.
4) Turn on your Pre. If you had to remove the battery, put it back in now.
5) Within a few seconds at most, (maybe instantly) you should see a large USB symbol that fills the screen of the Pre. Once you see that symbol, you can let go of the volume up button.
6) On your desktop run the WebOSDoctor. It should be a .jar file. When you double click on it, depending on what OS you have and what other software you have installed, it may try to open it like a .zip file. This is NOT what you want to do. If that happens, close out whatever opens, and then right click the WebOSDoctor and select "run with Java" or something like that.
7) From there, you'll get a nice friendly program that you will basically just dumby-click though.
*The whole process usually takes about 20 minutes, but 'can' take up to an hour.
**This won't work if your battery is below 30%, so when in doubt, charge it for a couple hours first.