Haven't had that happen. The one thing that really impresses me about the Tesoro's is how long a set of batteries work in them. Sorry about your luck, send it back, Tesoro is awesome about the warranty.
Hello fellow diggers....I know for a fact that the batteries were in properly...I believe I may have had a batt short out on me...it happens I guess....but even through it all...My Cortes still works!!!!!!!....Small coil acts weird now so it may have took a hit...hope not, it's a great coil....4.5 inch.....Steve in Tenn.