hiw to unlock Audi A5 Quattro with dead batterys

What is your question?

I own Audi A5 Quattro 2012 and because I was leaving the country for 3 months I was advised by my father to disconnect the battery in the car since I'll be away for this long! Now Iam back and I realized since I disconnected the batter I am not able to open the trunk of the car to re connect it again! I tried to look up for videos how to unlock the rink but couldn't find anything! Please someone guide me step by step how can I open it.