In the original solution, white plays @ a. However this loses, as shown above.
I propose , it secures an eye, and gives white the option to make another eye by playing a, b, or c. But it is black's turn, how does black kill now?
Obviously white @ a secures two eyes for white, so perhaps black playes there first.
But then we are back to a basic snap back position. Black kills the 5 white marked stones by playing @ a. So white dies even in this position.
So white really is dead, sorry I did not see that. Perhaps the above options are obvious, but probably not to all.