Pretty clear the pistons have seized in the cylinders. The oil leaks are from the rubber seals being cooked. The crank should be ok if there was oil in it. But at this point, the engine and the oil have been overheated to such a degree, that, unless you ran full synthetic engine oil, it's time for a total rebuild, including the heads. If it were mine, this is exactly what I would do.
And rather than kill my brother, or even slap him around, I would make him financially responsible. And if he did not look after things, I would make his entire life a living hell.