I have also fixed mine with the USBtinyISP.
A quick description of the process:
- Make sure external power jumper is REMOVED from USBtinyISP, plug in USBtinyISP to board
- Plug in EXTERNAL power to the seeeduino, and plug in the USBtinyISP to USB
- Set the seeduino to external power via seeeduino slide switch (USB/EXT)
- FOR LINUX USERS: start the Arduino IDE as ROOT
eg.: sudo ./arduino from your arduino directory - From the arduino IDE, select Tools\Burn Bootloader\ w/USBtinyISP
- Be patient, takes a minute or two - red light (RST) near external power connector will stay lit solid for the entire operation
HTH