Radio Code: Try This FIRST before anything else!
Note: This worked on my 95 Legend GS. I have no idea if it will work for other models as I am not familiar with any but my own.
After wasting a lot of time I stumbled upon an earlier post from V8Q that got me to the promised land. I went through the trouble of removing the console/dash in order to peer under my Bose Premium head unit and get the serial number. Then I went through the forums here and saw the number to Acura of Augusta. As others have stated they were very nice and immediately gave me a 5-digit code. I then spent the next several hours trying to get it to work. I would enter it and after the last digit the radio would beep but still display "Code". I tried it with the engine on and the engine off. I then disconnected the battery to reset the radio. And again I tried the different techniques. No joy. So this time I tried the posted trick of waiting an hour with power to the HU on. And again I tried the code several times. No dice. So I came back on these forums and ran across V8Q's posting about checking under the plastic fuse cover from inside the engine compartment. Right there on a white sticker is both my 5-digit unlock code plus the HU serial number. And as it turns out, the code that Acura of Augusta gave me was incorrect - not even close.
So the moral of the story is try the above FIRST. If you don't find the sticker in your engine fuse box, then call the Augusta dealership at 1-800-851-5158.
Some things I learned:
If you enter the wrong code in 3 times and lock yourself out, you DO NOT need to do the trick where you wait an hour with the HU powered on. It is much easier and quicker to disconnect the battery for a few minutes to reset the radio. Please be careful as batteries can be dangerous to the novice.
On my 95 GS the engine fuse box is immediately above the battery. You simply push in the two plastic tension tabs that face the battery and then lift up on the lid. Flip the lid over and you will see a diagram of the fuses. If you do have a sticker showing your code it will be very obvious. A white label with black type like a medium sized address label.
Again, this may only be for my series car, but the unlock code should be a 5 digit number, no alphas. The serial number should be a 10-character string starting with a letter followed by 8 numbers and then ending in a letter.
Once you have reset your radio and reconnected the battery, simply turn on your car's engine and make sure the radio is powered on. The display should say "Code" or "Radio Code". Next simply enter the 5-digit unlock code, slowly, and the radio will immediately come to life.
Good Luck. And thanks V8Q.