humminbird ice 35 question

[djremo]

quick question i tried to use my ice 35 out on bear lake this summer while jigging and it wouldn't work also had a vexilar on board and it worked fine so i called humminbird up and they say i cant use it on open water my warranty runs out in dec i just want to know if that's right that it is not supposed to work on open water so i can get it fixed it just doesn't make sense tome why not when you have a hole in the ice is it not open water to the bottom thanxs for any response
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