This issue is pretty typical. You install a new battery or re-connect the battery and your radio is now disabled and generating and error code. Why? -- This is a security feature and when the car is purchased new it will come with the reset code but many times when purchasing a used vehicle this code is nowhere to be found.
Watch this brief tutorial from MB Motorsports in Tinton Falls NJ on how to get your error code number, find the security code, enter it and get your system working again.
This video was based around a 2002 Acura CL -- but this will work with many of the Acura CL and TL after 2001. Hope this helps and enjoy!