The tree needs to be watered when the soil is dry on top, and damp underneath. Not on a schedule.
Stick your finger into the soil if you can, and determine how dry the tree is by how the soil feels. Then water it very well, from above, making sure that the water flows through the holes. Put the tree into morning sun/afternoon shade or lightly dappled shade, so that it can recover. Don't move it around. If it's in the house, it may be drying out from the air conditioning or fans.... which takes the moisture out of the leaves quickly. Been pretty hot in LA.
Find the best place to put it, where the sun won't bake it and the fans don't dry it out. Check it daily and water it when needed. Hopefully it will begin to put out new leaves (the leaves currently on it won't look better, they're pretty well goners) Keep picking off the scale, which is a very effective way to remove them without using chemicals. I would worry about using anything on it until it recovers.
Good luck!
Joanie