Ah yes, the classic fail. You've done it before, it caused you lots of frustration and now... you've done it again.
In my case it's the Raspberry Pi Zero v the Raspberry Pi Zero W. One was WiFI built in, the other doesn't.
I setup a new SD card, added the SSH file, the wpa file following my OWN instructions
And nothing. It wasn't appearing in the list of devices connected to my network. I thought my battery was low so connected the cable (after digging it out). I thought the network was slow so restarted that. Nada. Nothing. Zilch. I was contemplating plugging a screen in when the hubster asked the very obvious question: Is that a Pi Zero W?
Wasted a good hour on this. But you know, it happens. If you don't laugh and move along just cry... and move along.