Issue with pairing wireless keyboard/mouse after logic board replaced

Hi there. I just got my iMac G5's logic board replaced. When I started it up, my bluetooth wireless keyboard and mouse didn't automatically set up. The setup asst comes up and says no mice have been found. It also says make sure your mouse is discoverable. I have a USB mouse, which I plugged in and it works fine. Only problem is that I don't have a USB keyboard so I can't type in my password to proceed or even get to the system preferences section. Does anyone have an idea of what could be wrong and how I can fix it? Thanks.