Sounds like the AV software hosed it. Is there a reason why you installed AV software on this device? It doesn't run Windows Mobile, which is pretty much the only reason you would have to. Considering the age of that device, I fail to understand why you did this.
Now, as for the broken phone: try removing and reinserting the battery. If that doesn't work, try the "hard reset" thing on this page:
http://en.kioskea.net/faq/470-how-to-reset-your-nokia