So I did everything like You said, but when I type fastboot flash zip ruu.zip it says "error: cannot open 'ruu.zip
Do you actually have a file called ruu.zip on your computer? In which folder?
So I did everything like You said, but when I type fastboot flash zip ruu.zip it says "error: cannot open 'ruu.zip
Do you have file extensions showing on your pc? Make sure you didnt rename it to ruu.zip.zip