New MBP suddenly can't find any more Wi-Fi networks
Did you try to delete those network plist file?

Doing this you "Reset" the Wi-Fi:


Close your Wi-Fi from Macbook
From toolbar select -> Go -> Go To Folder
Paste this address /Library/Preferences/SystemConfiguration/
Locate and delete these files


com.apple.airport.preferences.plist
com.apple.network.identification.plist
com.apple.wifi.message-tracer.plist
NetworkInterfaces.plist
preferences.plist

Now restart your Macbook
Open your Wi-Fi and test again