I don't know about D/P, but I managed to change blast burn on HeartGold to physical by changing the third value to 00, as you suggested.
You may also have the wrong offset. The original hex for blast burn is 50 00 01 96 0a 5a 05 00 00 00 00 32 16 01 00 00. It may appear twice, but you should change the first one.