Two defective pieces in a row - unreasonable to demand refund?

Ohh I just now see his issue was resolved. Hope my above post is logged in as a alternative method of working out simple solutions. 
Compromise. This is the key.

You bought other products from this dealer and they won’t accept the refund after two defective units? Wow.

You should have an accomplice walk into the dealer pretending to be interested in some Macintosh equipment but they are hesitant because they read this thread.

In an age where many audiophiles buy used equipment and don’t buy new from a dealer, they should be bending over backwards for you. Especially considering that you’re a loyal customer.

Macs really hold their value. Id try to get compensated someway and take the third unit conditionally.

I would have the dealer get a third one but I would make it clear, third strike and I'm out. I would talk to him first and then I would text or email him a summary of your conversation. Start out with "as we discussed...."

Digital Mac's don't hold value. Sure get a 3rd, you must be looking for punishment.