[mapaz04]

Just in case you dont know how:

Flashing from SD card:

1.) Unzip the .rar or .zip file of the downloaded rom (if it is an .exe file, see if you can right click and extract...)
2.) Rename the Signed_RUU.nbh to RAPHIMG.nbh
3.) Copy file to the ROOT of the SD card (The image file should be found under the SD and not in a folder within it)
4.) Make sure the microSD is in your phone and send your phone into BOOTLOADER by holding the POWER and VOL - keys and softresetting.
5.) Your phone will automatically read the img file and ask if you want to continue (press pwr button) or cancel (press center circle button)
6.) Once flash is complete, phone will ask you to reset, soft reset and there is your new rom.

AS OTHERS HAVE STATED, PLEASE MAKE SURE YOU ARE USING THE RIGHT ROM... CDMA OR GSM (IF YOU HAVE A SIM CARD, YOU ARE PROBABLY GSM)