When downloading the new blackberry software 4.5 onto my 8810 the process encountered a "fatal error" and my blackberry screen now consists of a symbol of a circle, square and triangle with a diagonal slash and the numbers 507. Is there any hope to bring it back? I went t the AT&T store and they said that I needed a new blackberry (which I ended up buying). Is there anything I can do to rescue my old blackberry or is it truly fried?

Make sure you're using the software for your specific model. Don't load 8800 software on an 8820, etc. Then try the update process again, following the exact steps in the BB FAQ. You can wipe your BB with JL Commander before running the Desktop Software for the OS update if simply running the update again fails.

Check out references for JL-commander, although I think it may be abbreviated differently in thread. It might be in the FAQ sticky thread. You might also search for "brick" (they use the term "bricked" for a phone like yours)

I am not an expert but generally doing software updates should not permanently kill a phone.

justgoogle how to recover a nuked blackberry. It will give you step by step instructions.