This matches with what I've learned as well with digital B2C products. You should fully refund with a very low bar. No questions asked, even.
Assume the customer has a point, even if you don't fully get what the point is. If they are not happy for whatever reason, promptly give them their money back, apologise for the bad experience, and move on.
Furthermore, your customer support should never be defensive; their job is not to protect your company but really side with the customer. Early on, when every dollar counts, it's easy to fall into the trap of trying to argue with the customer to keep their money. Just don't do that, it will annoy the customer and you'll have to refund them anyway.
Yes, some people will take advantage of this, especially with refunds. That's the cost of doing B2C business, perhaps with digital products in particular where it's hard to prove the customer “received value”.
When they say ”the customer is always right”, as cheesy as it sounds, they have a point. And it's not that the customer is always technically correct, but assuming that stance will be better for your business.