Hi Ari
It sounds like you have damaged either the P2 I2C chip or the Sanguinololu ATMEGA MCU. One test would be to re-upload firmware to the ATMEGA with the Panelolu2 disabled to see if it works without the Panelolu2 connected. That wont completely prove the ATMEGA however because it does not test the pins for the Panelolu2.
Cheers
Tony
It sounds like you have damaged either the P2 I2C chip or the Sanguinololu ATMEGA MCU. One test would be to re-upload firmware to the ATMEGA with the Panelolu2 disabled to see if it works without the Panelolu2 connected. That wont completely prove the ATMEGA however because it does not test the pins for the Panelolu2.
Cheers
Tony