have you tried to reformat the JB3 then do a clean install. Basically just wipe it clean as a baby's but and start new, if possible.
Also, is this a new, as in never used JB3? What firmware is it currently running? Does the PC (either you tried) at least recognize the device when its plugged in? Mine likes to pretend the JB3 isn't there sometimes. If your PC is at least seeing the JB3 we can rule out connection isses.
Just to be sure... this is the way my firmware says to upgrade.. you're doing all this right?
1. UPGRADING AND VERIFYING THE FIRMWARE
------------------------------------
1.1 Upgrading the Firmware
1) Connect your player to a power outlet.
2) Connect your player to your computer.
3) Close all other software applications.
4) Double-click JB3Upgrade_1_40_06.exe and follow the
instructions on the screen.
5) When Windows informs you that the player is
detected, click the Upgrade button.
6) When the "Player is now rebooting" message appears
on your computer, and the "Please Reset Player"
message appears on your player's screen, your
player will automatically reset itself.
7) Click the Close button.
Detach your player from your computer.
1.1.1 Troubleshooting
In the event that your player fails to
automatically reset as described in Step 6,
manually reset your player by inserting and
pushing a straightened paper clip into the
Reset hole, which is located on the bottom of
your player.
Notes:
- When you reset your player, it may only
display the charging icon. Press the POWER
button to turn on your player.
- The player may also display the "Rebuilding
Library" message. Please wait while the
library is being rebuilt. This will take
a few minutes, depending on the number of
songs you have on your player.
In the event that your player fails to
successfully upgrade, it automatically
enters into Rescue Mode.
Follow these steps to re-attempt the
firmware upgrade in Rescue Mode:
1) Select the onscreen option "3: Reload OS"
on your player.
2) Follow Steps 1 to 8 as indicated in
"1.1 Upgrading the Firmware".
Might want to try try the above reload OS thing. Cause just with what you're saying sounds like maybe a previous attempt messed up, so its a little funny now. Thats why i was wondering if it runs otherwise.
my two cents on that. Any more information on what your doing will help.