Default TCL s950 cannot receive signal

Hello and thank you in advance guys , this forum is wonderful , I just started going deep into the world of android and found my self scratching my head at many occasions. I have great experience on PC's regarding software and hardware , too bad they are of no use when we talk mobile-phones. So , I got a TCL s950 some days ago , it had 4.2.2 android with English and Chinese language only, I decided to root it and flash a new ROM , I used your thread and got everything done-(the learning curve was a bit vertical for me , I nearly bricked the phone )- my phone boots and everything , it can use WIFI download apps and generally work fine .
Now the problem
Even though the phone can detect SIM instertion I cannot receive/make calls , send SMS , nothing. I can see no signal bars on the indicator whatever I do. I reset the phone back to stock ROM but the problem persists. Could it be a hardware failure? Modem issues? ROM issues? I really don't know... I've been working hours and hours on this , now the next step is to take it to a store and have them check it .
I would appreciate if there was a solution , I will wait patiently for anyone that can help. Good day to all.