A factory reset cannot restore the rom. By wiping system you also deleted your current rom.
To get back to stock, fastboot flash the stock images. There's a thread with full instructions linked in my signature
If yoga decide to root again, read the thread stuck at the top of q&\ labeled "read this before you root"
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Yes you can adb push a rom on to there but I'd recommend doing the above first. Simply because you didn't understand what you had done or why you did it means you have a bit more learning to do yet. Not trying to offend but being rooted needs knowledge so I recommend acquiring that before trying again.
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