Help! My car 2005 Savvy MT overheat then cannot start.

Today got stuck in traffic jam, then the car start to overheat. At 6 bar then I stopped by the roadside for, switch off engine fully. After 15 minutes restart the engine the see temp back down to 4 bar, I bravely reenter the jam and after about 10 minutes the temp shoot back-up and I pull over the roadside one more time. Wait for another 10 min then try to restart, but cannot. During crank sound like no power, battery low. Any ideas why? The car still by the roadside need to rush as got exam at school today, will deal right after this... Now cannot concentrate. Any suggestion is very much appreciated!

For you info just change the car rear brake pump due to leak, and done full bleeding just before the new year.

got few friend to check they think it is the fan... serve me right using cipalang radiator fan.

Sorry not clear, I restart after checking the temp go down back to 3 bar. I bravely reenter the jam because I know something is wrong with radiator fan. Have a full health check with the mechanic (perfection garage) everything is OK and now change radiator fan motor and everything is OK.