Samsung Galaxy Ace GT-S5830 neither goes into Download Mode nor RAM Dump Mode
Plug it into your computer and see if by some offshoot chance you have adb available.  If so, run a adb -d reboot-bootloader to reboot into download mode.

If that's unavailable, you are SOL and will have to have Samsung repair it.  Honestly, if it's hard bricked, you're better off buying a new phone...