Yes, I see the merrifield device briefly in device manager on windows, but it's replaced with the multi-function devices very soon after boot starts. (RNDIS, Storage, and Virtual COM Port).
Are you using 115200 for the baud rate in Putty when connecting to the console? I don't think you'll see any output if it's not set to 115200.
Failing that, do you have access to a linux machine that you could try? If you do, I'd suggest trying to do a "flashall.sh -b" with the latest image.
The '-b' option clears and re-creates the partitions, then flashes the partitions needed, including the rootfs.
The reason I say Linux, is that windows drivers (for me) have always been fiddly, due to windows being windows, and I haven't had much success flashing with my Mac, so I spend most time on a Linux laptop when doing that kind of thing to my Edison boards. It's easier to install dfu-utils to do the flash, and the serial drivers and gadget drivers all work on linux without any of the complicated setup you need on windows.
Rgds,
Dave.