avrdude: stk500_getsync() is a communications error. It cant talk to the bootloader... maybe wrong baud rate (in boards.txt) or even no bootloader installed.
Or just an issue with the auto reset (needs to be enabled and working, as boot loader only runs for 3 seconds after a reboot)
Different firmwares will not help, as long as they compile they should work. (as long as you have the correct board type defined)
So check you have auto reset enabled (normaly a jumper)
try a few baudrates in the boards.txt file for the Sanguino chip (normally 38400 or 57600) (reload Arduino after you edit these file to reload them)
If that fails get yourself a avr programmer, put your own boot loader on it. or even upload directly without a boot loader.
Or just an issue with the auto reset (needs to be enabled and working, as boot loader only runs for 3 seconds after a reboot)
Different firmwares will not help, as long as they compile they should work. (as long as you have the correct board type defined)
So check you have auto reset enabled (normaly a jumper)
try a few baudrates in the boards.txt file for the Sanguino chip (normally 38400 or 57600) (reload Arduino after you edit these file to reload them)
If that fails get yourself a avr programmer, put your own boot loader on it. or even upload directly without a boot loader.