I did one almost as bad. Every handful of dirt I picked up and stuck my pin pointer in would set the pin pointer crazy. Once I decided my pin pointer must be bad, I pulled off my gloves and then realized..... My wedding ring was on my finger.... Duuhhhh....
One beach hunt I did many years ago I was sweeping side to side for about 10 minutes. I wasn't picking up any signals at all.. That's when I realized my Whites Classic 5ID was turned off!