NodeMCU Wifi Module not found

Where is that function call to main() coming from? Do you have code saved that is loaded at boot?

You should get this, or similar, this is the output of a connection with screen:

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|   __|_ -| . |  _| | | |   | . |
|_____|___|  _|_| |___|_|_|_|___|
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Flash map 4MB:512/512, manuf 0xef chip 0x4016

>var wifi=require("Wifi")
=function () { [native code] }
>wifi.getStatus()
={ 
  "mode": "sta", 
  "station": "connected", 
  "ap": "disabled", 
  "phy": "11n", 
  "powersave": "ps-poll", 
  "savedMode": "off"
 }

In the terminal try issue a reset() first, this will clear saved code, then issue a save() then try again.