Can you tell us what type of beeps you are getting?
How many and how long, Also do you get any display on the screen?
The threee beeps would indicate a memory issue not a cmos battery issue, It is possible ( Not likely) that if your machine became too cold that the memory may have become unseated however I would like to start by looking at this first.
This guide will show yoou how to open and remove then reseat your memory http://www.5min.com/Video/How-To-Change-The-RAM-On-iBook-G4-Part-1-61115386
Once you have done that with the battery and power removed can you hold down the power button for 15 seconds then replace the battery and try to power up.
Let me know what happens.