I have not solved it, but I did have all the switches pressed at once by putting a bomb on all of the top row buttons, then I bataranged all of the bottom ones and blew the bombs immediately after, so all all of the riddler lights were switched off at one time but it didn't solve the riddle. I got bored with it and left.
Did that one this weekend. Set the explosive gel on the bottom 3 as the layout won't allow you to quick batarang the row. Once set, jump up to the roof opposite the question marks, which should give you a clear line of fire.
Detonate the gel, then quick tap the l1 to knock out the top three quickly. Then you can drop down and collect your prize.
Thanks for the small tips as I do truly appreciate them and I was able to acquire ALL Riddler Trophies, BO's, Catwoman Riddler Trophies, and Riddler Riddles yesterday. Only completing the remaining Combat Challenges remains.