Citoreon Berling 19 diesel Van?

Hi Have a citroen berlingo Van on an o3 plate 1.9l diesel. Put a new battery on yestereday as the battery light stayed on then after a while went off but it has stopped three times. Since putting the battey on it was ok for a while now shows battey light again.

Started up just now and the battery light went off but then the engine just stopped. Now can not start it engine does not turn over just clicks and the wind screen wipers come on when they are off on the stick

on the electronic display it shows a spanner and code 850 what does thi means please?

Thanks Roy & Matt