Does it boot to the Safestrap screen? (And are you using the correct version of Safestrap? 3.72 won't work on 4.4 and 3.75 won't work on 4.3.)
If you can get to the Safestrap screen, go into Safestrap (the button on the left), restore the stock ROM that you should have made a backup of as soon as you had Safestrap installed, and see if it boots into that.
Remember, you can only use ROMS that are modifications of Verizon's stock ROM, since the bootloader is locked. If Biggins or Hyperdrive aren't stock ROMS, the signature is wrong and the phone will soft-brick if you try to boot into them. (Which is why Safestrap is so great. You flash [on install into Safestrap] a ROM the phone can't boot into, and it's 5 minutes to restore a ROM that works and reboot. Killing a phone with Safestrap in it takes a lot of work.)