Hmm, I don't think that's the problem, I have multiple boards that use either 250000 or 115200 bauds and Arduino programs the fine, no need to change baudrates. I'd check the board for bootloader; if it doesn't have one, the upload won't work that way. Instructions for uploading without bootloader: https://www.youtube.com/watch?v=oZVTYpHnpIw