Default [Q] m8 Stuck on splash after SuperSu

I got a new HTC One M8 today and I might have messed it up. It is currently stuck on the splash screen "HTC powered by Android" on bootup but I can hit power+volumeDown+voluemUp to get it to reboot and use power+volumeDown to go into hboot.

Current Hboot status:
*** UNLOCKED ***
M8_WLV PVT SHIP S-OFF
CID-VZW__001
HBOOT-3.1.0.0000
RADIO-0.89.20.0321
OpenDSP-v38.2.2-00542-M8974.0311
OS-
eMMC-boot 2048MB
APR 1 2013,00:26:53.0

What I've done:
1) Used the WeakSauce method to unlock bootloader / S-OFF
firewater-soff <dot> com
Boots OK

2) Flashed TWRP recovery v2.7.0.2
Boots OK

3) Flashed SuperSu
Boots OK
No root

4) Tried combination of flashing latest SuperSu v1.99r3, older SuperSu, sideloading vs. installing, and clearing cache
Boot Stuck!!

The logcat I did only had the single message:
"- exec '/system/bin/sh' failed: No such file or directory (2) -"
So...I might have erased the /system partition or something else horrendous. Would flashing a ROM fix this? I could just install CyanogenMod...
Any help would be appreciated!

EDIT: I see that blank "OS-" in the hboot menu...that's not good.