Important: Your phone’s antennas are placed underneath the back cover. To get the best signal for calls, data connection, and GPS navigation, be sure to secure the back cover tightly to the phone.
HTC EVO 4G LTE into the bottom part of the back cover first.
Press the sides and the top part of the back cover against
HTC EVO 4G LTE to lock the cover into place.
You will hear a click when the back cover is locked in place.