This tutorial walks through what to do if the GPS lock does not work.
INSTRUCTIONS & INFO
If you are unable to get a GPS connection, use a longer Ethernet cable to move your MicroCell closer to a window with a clear, unobstructed view of the sky.
If a longer Ethernet cable will not resolve the issue, then powerline Ethernet adapters are available that use electrical outlets to provide Internet connections to areas away from Internet equipment. For example, if your router is located on a different floor or part of the house where you want to place your MicroCell, powerline Ethernet adapters can connect the MicroCell to the router through your electrical outlets. Connect the router to one adapter plugged into an electrical outlet, then connect the MicroCell to an adapter plugged into an electrical outlet in another part of your house, the two can communicate via the electrical wiring. A minimum of two powerline Ethernet adapters are required. One for the router and one for the MicroCell. Note: AT&T offers a HomePlug AV starter kit online at www.att.com. Similar devices are also available at local electronic stores. Continue to keep your MicroCell and router plugged into an electrical outlet using the power cord provided with each device.
If your issue cannot be resolved via the troubleshooting steps provided, please visit ATT MicroCell Help or call AT&T Support at: 1-800-331-0500