All unit needs a fairly clear line of sight to the satellites. Buildings, mountains, trees etc will interfere with the signal. The signals will not go through walls, roofs, vehicles etc...

Position the unit outdoors in a clear area turn it on and leave it on for 30 minutes. Hold it away from your body (signal will not go through your body) . Go to the satellite page & see it acquire the signals. If after 30 minutes it has not given you a position, take it ack to the store.

The GPS unit needs time to read the signals it receives, also the satellites emit different info packets at different time intervals. Turning on & off you GPS too often without letting it get the full readings will "confuse" it. So leave it on until you get a position ...