How to start a map remake?

Hello everyone. I was interested in creating a remake of the map "Donya fortress" from the Battlefield 3 dlc "Close Quarters". The problem is: how do I start? I mean, I have the blueprint of the original map and this allows me to have an idea of the proportions of it, but what for the map itself? I don't like the concept of doing it while trying to remember how the map was.
The most logic thing is to boot up bf3 and the map and see how it is made, but there are 2 major problems:
1) I sold my 360 to a friend of mine
2) I played the entire game on my brother's profile, that means that if I try to use it on my profile via backward compatibility i don't have any progress saved and I'm not allowed to access dlc maps...and Donya fortress was a dlc map..
One first solution I tought would be good was to grab a video on youtube of people playing on this level and take several screenshots, but I found this solution a bit out of place.
Do you have any ideas?
(P.S. sorry for my english).