For those of you having problems with the latest UVUAMDL firmware, this is because T-Mobile has added a SetUID restriction on the kernel. This can easily be solved by flashing a stock kernel with the restriction removed.
MAKE SURE YOU ARE ON UVUAMDL 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!