re: There is no damage to the canbus line.
So you've confirmed the bus terminators are correct resistance, that +12 is good, that ground is good ? 'Good' meaning within CANbus specs ? Canbus cable is correctly secured ? All connectors have been desconnected, cleaned, tested, reinstalled ? ANY signs of corrostion ('green' copper wire ) ?
How many modules are on the Canbus ? Typically there's' the ECU and dash. Are there more ?