I took it all apart, put it back together real carefully, trying to make sure that connection was pretty good. Fired it up before I put the cover back on, and found at one point that it was going back and forth between usb connected and disconnected, so it definitely seems like a bad connection. At one point, it came on just fine, went right to rockbox, but after I put the covers back on, back to the error message...frustrating. Also, at one point, I got an ATA -80 message, that was scary, but I can't find any info on that.
I am definitely no good with the soldering, so I'll look around for someone to help me out. In the meantime, I guess I'll get the backup 340 rockboxed and ready to go (hopefully!) Or maybe start getting more serious about the R-44 I've been wanting
Thanks for all the help!