As DfuSe seems to work for you, i'll create a file for it with latest bootlader/firmware later today. That can be usefull.
If you want to give another try yourself, only flash the pfm3 bootloader (p3_boot_1_09.bin) at 0x08000000 with webdfu on your Mac.
Then you should be able to boot in the pfm3 bootloader by pressing MENU while turning on.
From the pfm3 bootloader, you can easily flash the firmware (p3_0_110) that must be copied on the SD Card. Just read the screen instruction.
P.S : I confirm you cannot brick your preenfm3 : Boot0/DFU jumper on, always boots to a system (STM32) bootloader that cannot be erased.