In the future, it may be prudent if the op doesn't let himself get in a position where he only has 600rmb in cash to his name.

Having a bank account overseas or pre loaded travel card that can work at any atm in China, saving most or some of your salary away in rmb each month if not, can act as a buffer should things go south, as does a open return ticket home.

Granted, the OP may have been helping out family back home, but still....