Everything on the phone should still work.. You are right.. You will not be able to make phone calls or use a cellular data plan.. You are basically buying a high-tech PDA..You can use Wi-Fi for internet.. A possible reason for phone functionality is a broken cellular Radio, which connects to the cellular network.. Also, it could be a software issue as you say.. He might have incorrectly flashed the phone to a bad ROM.. That would make the phone function not work correctly by not enabling it to connect to the cellular network.. I have never personally had this issue.. But I have had it where my phone plan was turned off on my 6800, yet I could still use it fully (except to call and text).. Once you get the phone, ask in
here about how to try to troubleshoot the cellular issue..