Are you able to boot into your bootloader
On your PC or Laptop - reboot the machine. Once booted press the windows key + E. Navigate to your sdk folder and highlight the "platfor-tools' folder. once hilighted (single mouse click to highlight) hold the SHIFT key and left click the "platform-tools" folder. Select open command window here.
On your phone - Power down then Hold the Vol down button and press the power button. Hold both for a few seconds > release the power while continuing to hold the vol down button until the bootloader screen appears.
If this does not work try holding the power button untill you see the Back and Home soft keys flashing. Continue holding the power until they stop flashing. Immediately release the power button and push the vol down button. do not release until you see the bootloader screen.
Select 'Recovery' from the list to boot into TWRP.
Plug in your USB cable
On your PC or laptop copy the viper rom to you platform-tools folder. Now right click the rom file and rename it sideload.zip
in the command window you opened earlier type > adb sideload sideload.zip
here is a link to a sideload thread.
hope this helps.