I also tried nvflash -r --download 5 twrp-2.2.2-jb.img but it stuck in:
Unfortunately the only think you can do is wait and hope that the devs can find a workaround.
I got the same problem
I managed to unlock (UnLock_Device_App_V6) and root my TF201. then I installed GooManager to installed a recovery which I successfully did.
Then I boot into recovery and installed Jelly bean (us-tf201-jro03c-10.4.2.15-...
top left corner of the screen says "The Device is Unlocked", in the middle ASUS logo, bottom right "powered by nvidia tegra" will not boot, or boot into the bootloader, i do have nvflash enabled but not sure what i need to do to get it unstuck.