Here is a great video from & explaination from ParoXysm QC [x360a - x DIAM0NDZ]. Not mine just passing it along, so all credits go to the author!!.
Chapter 19: Burning Tower
Difficulty: Any
At the very end of the chapter, you'll have to quickly hack two devices to open the giant locked door (LB). You must ABSOLUTELY take advantage of the slow-mo that is provided by the Dart Overlay or you won't be quick enough. Don't worry if you fail, you can simply restart to the last checkpoint.