you will at least manage to get some refund in the end.
When you said some refund i wasn't thinking about value equal to 2 large pizza-s and a coca cola. And the value is in COUPON. Not only that they don't have anything for sale for months but also why would i even consider buying from them again.
you must be persistent
be patient
be professional
be persuasive
be polite.
tell them that 50usd is far too small.
ask for 1000usd in btc to an address for a refund
you are in for 3300 and have two working boards.
you should get 2200 usd
but are willing to take 1000usd.
point to this thread. tell them they have given much larger amounts to other customers.