my Chevrolet caprice not start even I change the charger motor ? on 2008 Chevrolet Impala

the battery signal start to come in the information screen then I change the battery after tow weeks the car stop suddenly ,I took the car to the workshop but they told me to change the charging motor ,when change it still the car not starting and the signal coming again
what do you think is the problem ?

Asked by for the 2008 Chevrolet Impala
the charging system is controlled by the ecm. seek diag and est