Closing the power liftgate makes motor like sound when it is latching down.. button on the tailgate works to close the tailgate but it always makes running motor like sound. Indicator inside the console shows red on the liftgate but actually liftgate is closed. So basically two problems: motor sound when closing and red indicator in the console.

I showed to local dealer and he diagnosed this problem to the bad striker. But he was charging $600 for fixing it - $400 for the part and $200 for the labor.. i already paid 150 for diagnosis. I took it back as not sure if it is worth the cost. Also I was not sure if that is correct diagnosis.. because it seems to me some motor issue than striker issue.

So I need help in figuring out what exact part I need to buy and how to replace it (if i can do it myself).

I researched and seems like there are 2 different parts available on audi website when searching for striker: 8P4827507 and 4F9827383G. Not sure which one to buy? from where to buy it and can I replace it? any instructions will help.