AudiA1TDI

Thanks in advance guys really could use some help

Hi there I have an Audi A1 tdi 2014 model, I have a number of issues which I would appreciate some help with. 1. Firstly thought the battery was dead so changed it myself and still wouldn’t start, then a friend jumped it using the connections under the bonnet and it started, idled fine, when switched off wouldn’t start again. I bought a brand new agm battery lion it was. So does that mean my alternator is dead? 2. Also I had an error code of p066e any ideas?