Remove the dead and dying leaves. Overall it looks fine unless you can post photos of the new leaves showing a major problem. Was the residue there when you bought it? I see a lot of plants from Florida (Home Depot and the like) where the plants were treated before shipping. Usually a wet sponge/paper towel can remove most of the residue. Leaving it in a shower without enough light is not good for it. It was enough shock for it being shipped hundreds of miles to live in a home when it was nice and happy growing in a commercial greenhouse.

Any sticky reside (honeydew) on lower leaves or the floor? Do you know how to test for spider mites? What are you fertilizing with? How long have you had it, and, have you ever done a full repot, and what kind of soil is it in. In order for new leaves to form normally, Ca(lcium) must be in the nutrient stream at all times. If the plant is not taking up enough Ca, or the flow of the nutrient stream is disrupted, new leaves emerge deformed, often with brown margins which turn necrotic with the necrosis extending inward. Your plant presents classic symptoms. The question is, is the deficiency caused by an actual deficiency where there is not enough Ca in the soil, or, is a cultural influence (over-watering, soil compaction, an excessive amount of Mg (magnesium) in the soil, a pH issue, ....? Low light, cool temperatures, high humidity also slow respiration which slows the nutrient stream which limits Ca availability which exacerbates manifestations of the deficiency - the malformed leaves. You don't offer enough info so I can't say what caused it to occur, but look first to over-watering. Going only by the odds, that's the probable cause. Al

It’s in a drainage pot inside the ceramic pot, it’s not been watered for about 2 weeks! I thought over watering too but I’ve only watered it twice since buying it in mid December! it could be cold As the house gets quite cold in the day? I’m just wondering if it’s salvagable? I’ve cut off the rotting bit and am hoping it helps 🤷🏼‍♀️

Roots look ok. Your plant would MUCH rather be repotted in June (if you live in the N Hemisphere) than in the fall. "It takes a while" is too vague to help us decide how appropriate the grow medium is/isn't. I suggest you start using a "tell" to "tell" you when it's time to water. See "Tell" below. The all-important question is 'what to do to save it'. The answer to that, though broad, is, examine the cultural influences under which the plant grows. At least one, maybe more are asking the plant to deal with conditions it's not genetically programmed to deal with. This Overview should help you decide what needs tweaking. Using a 'tell' Over-watering saps vitality and is one of the most common plant assassins, so learning to avoid it is worth the small effort. Plants make and store their own energy source – photosynthate - (sugar/glucose). Functioning roots need energy to drive their metabolic processes, and in order to get it, they use oxygen to burn (oxidize) their food. From this, we can see that terrestrial plants need plenty of air (oxygen) in the soil to drive root function. Many off-the-shelf soils hold too much water and not enough air to support the kind of root health most growers would like to see; and, a healthy root system is a prerequisite to a healthy plant. Watering in small sips leads to avoid over-watering leads to a residual build-up of dissolved solids (salts) in the soil from tapwater and fertilizer solutions, which limits a plant's ability to absorb water – so watering in sips simply moves us to the other horn of a dilemma. It creates another problem that requires resolution. Better, would be to simply adopt a soil that drains well enough to allow watering to beyond the saturation point, so we're flushing the soil of accumulating dissolved solids whenever we water; this, w/o the plant being forced to pay a tax in the form of reduced vitality, due to prolong periods of soil saturation. Sometimes, though, that's not a course we can immediately steer, which makes controlling how often we water a very important factor. In many cases, we can judge whether or not a planting needs watering by hefting the pot. This is especially true if the pot is made from light material, like plastic, but doesn't work (as) well when the pot is made from heavier material, like clay, or when the size/weight of the pot precludes grabbing it with one hand to judge its weight and gauge the need for water. Fingers stuck an inch or two into the soil work ok for shallow pots, but not for deep pots. Deep pots might have 3 or more inches of soil that feels totally dry, while the lower several inches of the soil is 100% saturated. Obviously, the lack of oxygen in the root zone situation can wreak havoc with root health and cause the loss of a very notable measure of your plant's potential. Inexpensive watering meters don't even measure moisture levels, they measure electrical conductivity. Clean the tip and insert it into a cup of distilled water and witness the fact it reads 'DRY'. One of the most reliable methods of checking a planting's need for water is using a 'tell'. You can use a bamboo skewer in a pinch, but a wooden dowel rod of about 5/16” (75-85mm) would work better. They usually come 48” (120cm) long and can usually be cut in half and serve as a pair. Sharpen all 4 ends in a pencil sharpener and slightly blunt the tip so it's about the diameter of the head on a straight pin. Push the wooden tell deep into the soil. Don't worry, it won't harm the root system. If the plant is quite root-bound, you might need to try several places until you find one where you can push it all the way to the pot's bottom. Leave it a few seconds, then withdraw it and inspect the tip for moisture. For most plantings, withhold water until the tell comes out dry or nearly so. If you see signs of wilting, adjust the interval between waterings so drought stress isn't a recurring issue. Al