This situation reminds me of my old tries (no luck) to restore using these images:http://pocketworkstation.org/files/recover/
Interestingly the image name for 860 is:http://pocketworkstation.org/files/recover...not-working.zip
...some bits from http://pocketworkstation.org/files/recover...ash-recover.txt
* Do a full reset. For the C700: Switch the battery lock switch (on the bottom)
to "unlock", and wait 5 seconds. On the C750 and C760, you also need to
remove the battery and the power supply.
* Insert the CF card into the handheld.
* Hold down the <C> and <D> keys simultaneously, and while holding them down
switch the battery lock switch back to "lock". On the C750 and C760,
re-insert the battery and reconnect the power supply. Release the keys.
* Both LEDs should switch on and stay continuously lit - this means the
flashing process is working. DO NOT disturb the handheld at this stage.
* After a minute or two, both lights will go off again. Power cycle the
handheld by switching the battery lock switch to "unlock" and back to "lock".
If the LEDs start flashing, an error has occured, and it has given up
the flash process in an unfinished state.
* Hold down the <OK> button (either one) and while holding it down press the
"On" button at the back of the handheld. You should get the japanese system
menu, and should be able to use it to restore the rest of the flash ROM.