I’ve got a Switch off of ebay for cheap and wanted to see if I could fix it. This one clearly has some corrosion going on, so maybe it just needs a cleaning, idk yet. Anyway, there is a lower case F written on it with marker or something like that. Has anyone seen something like this before or knows what it means? Not sure if it has already been opened before, I kinda doubt it since I bought it in a bundle with a bunch of stuff including the retail box etc.
Here’s an image: