So I got my 4000 working again, downloaded a restore image for a 6100 and did a restore onto a 8GB standard SD card. Booted right up as if new, it even had my phone in bluetooth memory and connected! Firmware reports 1.05. So far haven't tried all the options, but HD RADIO and BT are working. I tried a quick firmware update but that has always been a challenge with these devices and it says my firmware upgrade USB stick is not set up properly.
I can't remember where I got the image, but it was off the site here. Filename AVICimg6100.zip if you want to look around. I believe it was a post that said something like "Lets post our backup images" or something like that. Look in the development mod post. Hopefully you're good with dd, if not I can help with that.
If you can't find it I'll look at sending what I have to you direct but first I want to test it more to make sure it's working good.
Will report back later today.