I tried to unroot my Galaxy S4 by using galaxys4root.com/galaxy-s4-tutorials/how-to-unroot-galaxy-s4-and-remove-root-completely . I downloaded the verizon rom from galaxys4root.com/galaxy-s4-stock-firmware/ When I click on the 'PDA' button and select that firmware file, it has a red box that says "FAIL!" The last few log entries are "aboot.nbm", "", "Complete(Write) operation failed.", "All threads completed (succeed 0/ failed 1)" Now I get a yellow triangle when trying to boot the phone. How can I return back to stock?