My cheap exit would be to add some USB WiFi stick. These run under 20 dollars and far cheaper than repair shops.
Lenovo might use some Fn+Fkey combo but as you own this I think you would know and try that key. Since that failed, your cheap fix is the USB WiFi stick.
I have a t420 running Win 7. Coincidence or not, a dog knocked it over and since then I have no WiFi.
I have checked and found no physical switch.
the wireless adapter appears to be enabled.
I am connected to an Actiontec C1000a via ethernet at the moment supplied by CenturyLink.
There doesn't seem to be any download associated with the Actiontec.
Thanks for any help!