Step one you need a SD card that has less than 32 GB, the perfect card is a 4GB or 8GB SanDisk brand one.
Step two you need a serial USB adapter, I recommend a CP210 based model.(this is the only way you’ll know what’s going on while you are flashing your control board).
When you have these two extremely cheap items you can complete all instructions with a little help from us. No need to mail anything anywhere.