Difference between 坏 and 破
“坏” is a very general word meaning something "useless", but what makes the thing "坏了" has many reasons, and “破了” is one of them, so when something's state is “破了”, you can also say something is “坏了”；However “破” means something is broken or has cracks. So when you describe something that is useless because of inner reasons such as quality, but it still looks nice in its aspect, “破了” is no longer used.

Try to compare the two sentences：

1）这热水袋破了（The warm-water bag is broken, maybe is of cracks by falling down onto the ground）.

2）这热水袋坏了（The phone is useless, maybe it doesn't keep warm anymore but NOT of cracks）.