I know there are some people stuck with a dead Moto G that has an unlocked bootloader and the shop where they bought it unwilling to accept the responsibility to honor warranty claims. I just received confirmation from a large online retailer - Bol.com that they are honoring my warranty claim for precisely this issue.
The defect was that the phone would not power up anymore at all; similar to a couple of cases I have read about on these forums. Important: the phone went dead within 6 months of the purchase.
The way I managed them to honor their obligations was to contact thuiswinkel-waarborg and file a complaint.
In this complaint I made sure to point out that warranty was declined without providing proof that unlocking the phone had been the cause of the defect. Since the burden of proof lies with the seller within the first 6 months, they were in breach of the regulations from thuiswinkel-waarborg by refusing the warranty claim in this manner.
The seller tried to convince the hardware service center to fix the phone under warranty but was unsuccesful. Too bad for the seller, but this is the risk they take on themselves; this has no impact on the rights to warranty that the customer has (at least in Europe)
Personally I opted to receive a full refund since during the several weeks it took to convince them I am right I got another phone. My next phone will be from a manufacturer that does not void warranty when unlocking/rooting since I can't be bothered with going through these discussions every time a phone dies (which they seem to keep doing all the time these days)
If you have further questions including details about the email and phone conversations I had with the seller please send me a PM.
Especially if you bought your phone at Bol.com you may be interested in a referral to my warranty case, in order to strengthen your own warranty claim. I will do all I can to help out any of you who are stuck in the same position and have not given up on getting compensated, as the law requires.