Anyone know anything about Avaya 4400 phones?

I have an Avaya 4400 series phone here at work and I broke it again. Last time it took our phone guy 2 weeks to come fix it. I tried to program in a handsfree answer button and now I can't make phone calls. I cannot pick up my line without selecting the line, then I can hear the person on the other end, but they can not hear me. And I can't disconnect the line. I don't knwo what happened but this happened before. I didn't try to program over the line buttons, but now they won't work. Does anyone know what I can do to fix it?