I have had a great season last year with my fisher f75,i love it!! but,I went to use it today and it chatters and signals relentlessly,in the air on the ground,no targets around and when there are known targets,it doesn't pick up on them at all.I removed the coil.same issue,plugged it back in checked connection,no difference. I replaced the batteries...no difference.I factory reset it, after the reset it went quiet all right,but wouldn't pick up any signal,till I fiddled wit the settings and again we were back to the relentless chatter.I switched the frequencies. I did not have my phone on me and i'm not around any wires or power sources out side.I put the detector away in the fall with the same settings that I always use so it had not been touched all winter..I'm at a total loss as to what could have gone wrong..any ideas?