My battery died overnight on my 2016 Doblo 1.3 multijet. Charged it up (on the chargers recovery mode) for a whole day. 13.6 v shown, so turned the motor over. Just a click and battery down to 8.2v immediately.
Bought a new battery the next day, fitted it, started fine. But speedo flashing, no radio, no aircon, and running a bit lumpy. The general concensus was that it needed to go on Fiat's diagnosis machine for a "proxi alignment". Rang Fiat independent who said he could look at it in two weeks.
Spoke to my neighbour about this, and he had an Autel code reader. Plugged it in, and found ODB port dead. Checked fuses and found F35 fuse blown. Replaced and all back working fine, car running perfectly.
So why the blown fuse just changing the battery? I'm extremely careful when attaching chargers to the right posts (ever since an RAC patrol man jump started my VW T5 with the leads the wrong way round and blew a £1100 ECU).