For those of you having problems with the latest VPUAMDL firmware, this is because Sprint has added a SetUID restriction on the kernel with the latest update. This can easily be solved by flashing a stock kernel with the restriction removed.
MAKE SURE YOU ARE ON VPUAMDL build OTHERWISE THIS KERNEL WILL BREAK THINGS IN YOUR PHONE!
Then follow the rest of the steps to install CWM SuperSU zip file in recovery.
Credits – XDA <— Please donate to developer or hit “Thanks” button on XDA if this has helped you!