All available firmware is here http://www.filefactory.com/f/4e1ce47f16313c0d/ but you probably will not be able to go back as a RUU will usually change radios, hboot, etc. *Reason to not jump on board leaked software immediately*
download, follow instructions run it. i was having trouble figuring out how to go back and this will return it to stock rom if your having issues with 1.85...
THIS WILL COMPLETELY WIPE YOUR PHONE!
ALSO MAKE SURE YOU HAVE A ROOT... after completely going back to stock rom, it will get rid of the root to however