A close mate maintains "big" helicopters in out of the way places in north west Australia servicing the oil and gas industry. If there are persistent warnings which they know to be false, they shut down, disconnect the battery/batteries for 5 mins then re-start. Almost always, the warnings disappear! He's been in this occupation for over 20 yrs and said they've never had a major mechanical malfunction, such is the mechanical reliability ...but the avionics are so complex, it's inevitable re. spurious warnings/error messages