Are you sure it's the detector? Here's a couple of suggestions...
1. Check the batteries. Are they inserted fully/correctly? Are they fully powered??
2. What type of ground were you hunting? If the spot or soil was very 'hot', might've drove your detector 'crazy'. Could be highly mineralized soil.
3. Were you hunting near power lines or transmitters of any sort? Even being a couple hundred yards away could do it.
4. Were your settings correct? Too high?? Setting your detector's senitivity too high can cause it to become unstable.
5. Did you get the unit wet at all? Make sure.
Bounty Hunters are fairly decent beginner units, but, they're not the greatest of detectors - in terms of function AND build quality. However, the unit shouldn't conk out after just a week or two. Try the above. If all else fails call Kellyco & pitch a fit. If they want to do the right thing, they'll help you out