If you are saying there is no output at all on the console port when you boot up. You have probably destroyed the flash files needed for boot with those commands.
The correct way to reset the device is with either load factory default or request system zeroize
https://kb.juniper.net/InfoCenter/index?page=content&id=KB23787&actp=search
if you cannot log into a device you use this to access single user mode.