Nokia Lumia 535 Display Light Solution Jumper Ways
https://gsmfixer.blogspot.com/2016/02/nokia-lumia-535-display-light-solution.html
Microsoft Nokia Lumia 535 Display Light Problem may be related to the cable connector between motherboard and LCD or this fault is concerned with the Display Light IC too. So initially you go for connector test and test for missing points.
If everything is OK there then you have to adapt alternative solution for Nokia Lumia 535 Display Problem Solution which is jumper way solution. All you have to do is to track the points to make jumpers as provided in the diagram. See the diagram to repair Nokia Lumia 535 Display Light Not Working Fault.