The beta firmware is still brand new (posted in the last week or so), and is specifically intended to address "no sound" issues - it doesn't sound exactly like what you're seeing, Cybermynd, but it might be a good place to start.

I thought I'd seen a post or two from folks who had successfully used USB/serial adapters for the firmware update? This post by ragnar suggests that it can be done, while this post suggests certain adapters that may be most reliable.