I am new to palms and received my first palm, chamaedorea metallica, a week ago from an online seller. upon arrival the plant looked healthy but had some weird looking variegation on its leaves with the metallic sheen portions surrounds by a black border (see below)
as the days have progressed the leaves have gotten a white rim around the metallic sections and very stiff and dry. the plant is still in its nursery pot and needs a repot but i’m trying to let it acclimate first. 
any insights as to what may be going on would be much appreciated!

Hello everyone!!
I recently received this palm from a seller on EBay. It came with its stem wrinkled and a broken spear. The stem is still hard and not mushy. How can I save this palm? Thanks!!

Chamaedorea metallica is one of the neatest and most unique species in the genus. It is one of the easiest species to grow and should be much more available. Each solitary stem is the diameter of a pencil and bears dark green bifid leaves (pinnate form is rarer) with a bluish sheen that gives it its name. And it is able to tolerate my alkaline sandy soil. I planted an understory grove of them in our back yard jungle. They flower and while I've yet to find a single ripe seed, I've noticed small seedlings popping up. I also place pots of them around the jungle. Here's to a palm that needs to be seen more.
Chamaedorea metallica, Cape Coral, FL 2021

Pinnate Form

A week or two ago I bought a Chamadorea Metallica from a seller on ebay. It arrived looking stunning! It still does looks the same. Although, the day it arrived I noticed that it had a small black spot on the trunk on the trunk (where the remnants of an old leaf had been). I asked the seller and they said that it was from when their was a stain on a leaf and it stayed on their too long. And they just should've removed the leaf, but didn't remove it quick enough. So they said its made a stain on the underlying leaf(s). So now the "stain" is spreading and its getting worse. How many leaf layers could a stay like this go through. The seller doesn't know what it could be other than that. The're almost positive that this is all it is. But, they've said they'll replace it if it goes downhill. The seller tells me that the specimen will be fine, and that it'll not be hurt. But, I worry about it since its otherwise so very nice. 
When I recieved it on Sat/Sun July 22/23rd, I immediatly potted it up. And then I watered it, accidently giving it too much water. The next day I noticed mold on the soil's surface around the bottom of the trunk. I checked the soil to see how wet it still was on Thursday July 27 (every day I noticed mold, which I removed). I realized that none of the water really had drained too much. The soil was still very saturated. The pot I used has drainage holes in it, and a drainage tray to catch water. But, I guess due to the fact that my apartment stays around 70F-75F, it didn't dry too much.
Well, I immediatly repotted it in fresh dry soil. I made up a fresh mix, this time I went with a fast-draining soil (the first time I mainly left a lot of Peat in there since I thought it needed to stay wet). The seller has informed me that this palm can go a while without water. So now I know this. They told me to lay off watering for 1 week.  
This new mix I potted it up in, on Thursday I know drains well. I went with a mix that is composed of "Miracle-Gro Cactus, Palm & Citrus Potting Mix", "Miracle-Gro Perlite", and "Sand". I've used this for years on my Washingtonia Robusta, and everything else from my Dracaena Marginata and even my Pachisandra Terminalis. I use it for every specimen pretty much. Its never let me down.
I've not seen any mold now since I repotted it on Thursday with the new fresh mix. But, the spot (that was present upon arrival) was still there. The seller instructed me to remove the remainder of the leaf that had the spot. Well, I did this and the underlying leaf also had a spot (albeit smaller at that time). Since then the spot on the underlying leaf has gotten larger and I worry its going to eventually spread to kill off that leaf (probably will take a long while though). The palm fronds show no signs of stress that I can see. It pretty much still looks like it did when I unwrapped it out of the shipping box. But, nonetheless the seller has told me to avoid watering for a week, see how it does, and get back in touch with them with an update on it.
What could be the cause of this black spot? Is it fungus? Is it bacteria or something? Is there anything I can do to stop it from spreading?  
 
What it originally looked like when it arrived.  
            

 
What it looks like now. I removed the leaf remnants as the seller instructed. It reveals the underlying leaf, with a small spot on the edges.