So I have a TSU2000 (sys 4.4) that I've been experimenting with for a couple of days. It's been acting normally for me as I bounce different CCFs into it, getting used to Tonto after a 10 year absence from the scene. Unfortunately, after sitting on the table next to my laptop for a few minutes, it quit responding. In fact, it seems bricked.

My resuscitation process has included:
Reset button (no effect)
Firmware reload with sys 4.4 (failed)
Firmware upgrade to sys 4.8 (failed)

The firmware upgrades failed after the updater told me it couldn't preserve the CCF, and I told it to keep going. Half a progress bar later, I get a dialog box that said the "Download Failed!". 

Now, all of this has been done with a USB-Serial adapter that's proven very reliable to me for a long time (FTDI chipset). Tonto has been running on both my Powerbook (OS 10.5.8) and my wife's PC (XP sp3). ProntoEdit on my wife's PC failed to see the remote after it went dead, as did Tonto. 

Short of giving up and buying another, are there any good suggestions about how to un-brick my Pronto?