Can I return a mod if it is unused?

From my experience the short answer is no. The extended answer is go right to the manufacturer website explain that it is unopened and you regretfully admit being naive and you purchased the wrong mod and since then have become more versed in the matter and have now purchased the appropriate device, however; the location you purchased from has a no return policy. Which is why you are contacting them in hopes that with the proof of purchase and the unopened device they would so kindly refund your money. Most of the time you can even get them to email you a return label so you do not incur any additional cost as you have already invested in two devices leaving funds a little tied up at the moment

Don't know if you can or not