I had the same problem today went to Verizon & was told we have to ship you another one. It will take two days or pay $9.75 for next business day. I paid the extra & had them order a replacement (Refurbished of course).
Anyway I came home did a search & found this forum. I read above on how to get into the boot menu. I was playing around & have gotten my phone working again.
Be warned I had to clear all data on the phone itself in order to get my phone working again. When I restarted it was like it was brand new had to go through all the reprograming & setup screens.
This is how I did it.
I don't think it matters but I had the usb cable plugged into the computer during this.
1. remove the battery to stop the endless restarting loop.
2. Press and hold the joystick when powering up the phone to bring up the boot menu.
3. Use the volume toggle to highlight "bootloader".
4. Use the power button to select "bootloader".
5. Use the volume toggle to highlight "clear storage".
6. Use the power button to select "clear storage".
7. Use the Volume up to confirm Yes (Clear)
8. wait 60 sec for it to clear. It will reboot on its own.
9. Once the phone is finished rebooting it should be restored to factory setting. I had to call into Verizon & reprogram the phone as if it was new.