I have described how I would handle a situation like this, considering client has a proof of order, I would do RMA on-site for him if he just got the product and explored few defects out of the box. However, I will wait and see what PiMAX would propose next. Hopefully we can fix it with an ease.
PS: And nothing of what I said is unrealistic, sending new one and get the old one back instead of making the customer send, wait weeks...and then send back new one. Is actually a good courtesy a company can take in such case where the product came with a couple of out of the box defects. Postal / delivery companies can do that service, conditional delivery, deliver new one and take the old one to the sender.