Hi,
Welcome to Fiat Forum.
A flashing Odometer is an indication that the CAN bus configuration is not what the system expected (you changed the instument node). The cure is simple, plug in a Fiat specfic diagnostic computer and run a "Proxi-Alignment" routine. A Fiat dealer can do this or you can use Multiecuscan (MES) www.multiecuscan.net with a USB ELM327 interface (and probably an adaptor lead). If you intend doing your on work on Fiats it's worth getting MES. If not, where are you located? A member may be able to help. I can do it if you are near Cambridge.