This sounds VERY bogus. No picture of your phone, or any explanation! Without hard evidence, your claim, which is first of its kind, is unverifiable.
Moreover, how do you know for a fact that it was Anker Battery that caused the meltdown, and NOT exposing your phone to direct sunlight for a prolonged period, though HTC specifically & expressly warns against it on the Manual!
Furthermore, Ankers are well praised for keeping cool temperatures.
Conclusion:
The only plausible scenario is that you were running your GPS while driving, with your phone hung in direct sunlight, for a long time. I believe this is how you killed your previous phone ( HTC Desire ) as well, only you blamed it on a faulty motherboard.
Advice:
My experience with driving with GPS on, and phone in direct sunlight cause these phones to heat up to fierce temperatures and something will inevitably break - my HD2's previous digitizer, for example. So, it would serve you better to put your phone away from sunlight if you use it as your daily GPS device.
better luck with your next phone, and I hope u remember my advice.
P.S. And, don't think your Samsung Galaxy SII is immune to this!!!!