Flashing odo is the general idicator of a CANbus error with Fiats:
Something attached to the CANbus has failed to respond during the pre-start checks.
It maybe you just need to leave the car with the ignition on a little longer to complete the check before starting. Or something may have failed and needs looking at.
Also if something has recently been replaced a "proxy alignment" normally
needs to be carried out so that the CANbus recognises it.