Thanks for pics that is VERY VERY much better.
Okay... the almost white strips at the top- looks a little sun-burned actually.
Teh necrotic brown areas... This is not good- Calcium def possibly but also a possibility of ROT.
My next question is, at any point in the plant's life, did you pot it up so that the level of the soil surface was ABOVE the original location of the first leaves (cotyledons)? I ask this because of a couple things... one, in one of the whole-plant shots it kind of looks like that big side branch is really close to the ground and if you have lower leaves and lost them early in the plant's life, you probably would not have a big branch that low, and two, the pic of your hand holding the newest growth tip, for the fresh growth to be necrotic like that, I fear that you may have rot in the roots or even the stem, if as I suspect part of it is underground.
Serenade that you can get at walmart you can use as a soil drench and it is safe to use on food crops, it's just a beneficial bacteria that kills fungus.
In the meantime, a foliar feed that has a good amount of Ca and K in it, and don't worry about the 'burn' because that looks like a very bad Ca lock-out rather than a fert burn in the usual sense, and make sure your soil pH is correct.
Nice variegated schefflera BTW.