May be a software malfunction or the connection to the GPS puck has come loose. My Humminbirds will glitch and lose GPS occasionally; restarting the unit has corrected the errors in my case.
plug the connector back in and tape it.
Many living in this generation shall never see the grave, JESUS gave us revelations and the time is very near. Dont be a soul that stands before GOD on judgment day and be told "depart from me, I do not know you".
REPENT, RECIEVE, REJOICE!!!