OK, Make sure the file on your SD card says EXACTLY PC36IMG.zip, not .zip.zip Windows by default hides file extensions, so name the file on your PC to PC36IMG, then transfer to your SD card.
Then power down your phone, wait 10 seconds.
Hold the volume down and power until the white screen appears. Just leave it alone for now...wait. Your Hboot will scan for the file. Once it finds it, choose the appropriate function and press power.
Do not pull your battery, let it finish. It may take a while.
Post what happpens.