Instinct temperature sensor broken??

Hi, it' s 3 days that the temperature widget on the instinct show a fixed temperature of 299° celsius...tried to switch on/off, put the instinct in cold water for 30 min, clean all the watch..no way...always 299°!!.the watch is out of warranty...and i think the temp.sensor (dont know where it is) is broken. Someone have the same problem?do you know how to fix it?tnx!Alex