for food to be cooked to specification, I'm a little confused as you state the burger was "dry," yet it was apparently undercooked.

All the meats and burgers I have ever cooked have been dry when they are "well" done.

Was this a very thick burger where the very deepest center might have stayed a bit pink, even though the burger appeared "crispy" on the outside?

Sometimes very thick burgers are hard to really cook them well-done.