car radio question

Hokay so... about a month ago or so I had to get a new battery for my car and when I got it back, my radio was saying "Err-3" on it so i disconnected it and reconnected it again to see if that would restart it and it would work again.. bla bla bla i'm totally illiterate with cars so i have no idea what i'm doing. So i got my boyfriend to help me out and apparently the anti-theft system requires me to insert a code but the guy i bought the car from didn't give me the code for it and i pressed a bunch of buttons already that i'm thinking maybe the chip in there might not let me enter anything else... okay so.. the question is, anyone know what the code could be or where i can find it? I took out the radio and looked on the back but there aren't any codes that i could enter and i've already pressed a bunch of buttons i don't know whether that would mess things up or not. Just need some help because i'm really trying to avoid spending 80 bucks at the dealership to get it fixed.

is the radio stock? or aftermarket? if it's stock call up the vendor and ask. if it's aftermarket just call whoever makes it and explain what happend. that's pretty funny btw

yea you can call your local acura dealer and get the code from them, but they do charge $$ to get one, although its way cheaper then $80