You could switch the servo connections at the receiver, i.e. swap the throttle for the steering. If the steering servo still did not work, then it would rule out the receiver. I also have a cheap servo tester that I bought from HobbyKing for about 7 dollars. It lets you cycle the servos, thereby testing them. If the servo is bad, you could recheck the inside connections/solders. Pull the servo out and unscrew/open the case. If everything looks good on the inside then it is probably bad (fried circuit or capacitor). There is not much you could try with the transmitter other than reverse, change travel adjustments, etc. Just disconnect the servo arm from the steering assembly first. Good luck.
Al