Ive found this
fastboot erase cache
fastboot oem rebootRUU
fastboot flash zip <path to zip>
though I have to find a ruu that has a mainver? that is less then the mainver my phone currently has. I tried fastboot get var all but I dont see mainvar.
I tried a few RUU's but all seem to get a "12 signatures failed message
I ran "fastboot getvar mainver" and it turns out I have no Mainvar :|