Unfortunately, you probably have a paperweight. If it is no longer responding to a hard reset, that's bad news. Sounds like you've run through all the normal troubleshooting steps.
I don't know if using TFTP to force a firmware flash is possible, same thing goes for JTAG (like recovering a bricked router).
As for the other things you mentioned near the end of your post, anything that ventures into opening up a Slingbox is strongly frowned upon here. You might try asking that question on a general discussion board instead. I like placeshiftingenthusiasts.com for general talk.
Another option would be to ask Sling to fix it as an out-of-warranty repair/replacement. You'll have to pay for it of course, but you'll end up with a working unit, it'll be cheaper that buying a used unit and you won't take the risk of getting another brick in the mail. It's way cheaper than buying a new Slingbox.
For $100, it looks like Sling will fix it or send you a warranted refurb. Here's a link that covers that stuff:
...and here's the relevant bit:
(Click to Enlarge)
If you decide to just upgrade and start over, there's a $50 discount off current models if you have an old Slingbox.
Hope this helps,
Thanks for the reply. I might pop over to the forum you mentioned tonight. I probably wouldn't bother having it replaired/replaced, since it's not that important to me, but if it was, I see there are some used Classics going for around $50 on eBay, so that might be the way I would go. Oh well, I guess I'll keep it around for a bit in case anyone else has a suggestion here or at the other forum, and then throw it in the parts bin. Thanks again.
I see there are some used Classics going for around $50 on eBay
Wow. They were notably higher last I checked. Cool ! I love my Classic.
Yeah, check out the Place Shifting guys when you have a chance. If they can't figure it out or offer offer any suggestions, I'd say head for the bin.
Good luck !