OK, your fuse setting seems to be ok, regarding this page:
https://github.com/rayshobby/opensprinkler/blob/master/OpenSprinkler%20Controller/software/arduino-code/hardware/aopensprinkler/boards.txt
This command is only when you have a blank mcu, to load the bootloader and the firmware:
avrdude -c usbtiny -p m644p -B 1 -F -U flash:w:combined2.1.2_16mhz.hex
After that, can normally update you mcu with the OsfwUpdater, with the usb port.
Can you send the log file ‘log.txt’ of the OsFwUpdater ?