You didn't mention it, but this is just case you have the X-1 probe and its switch box on the search upper shaft.
You may also want to try an alternative battery pack.
You also haven’t mentioned that you have done a system reboot to bring the Explorer back to the onboard defaults by holding down the power button on the detector during the boot up..
Other than doing what or the others have advised,it would require a different approach , like sending it in to Minelab.
There is one other REMOTE possibility that I am aware of and that I have experienced, but you would only consider doing this only as a last resort <span style="background-color:#ffff00;">and on<span style="background-color:#ffff00;">ly if your detector is out of warranty</span></span>. Doesn't involve much, basically opening up the control box and inspecting to see if "things" are in "order".
Like certain wires are still properly insulated.
If there is any indication of such a problem it is quite obvious and you should be able to tell.
Maybe take a digi pic and of your viewing perspective of your Explorers internals at the point of when you just pry it open( you do not need to pull apart the shell TOO much , just enough to be able two see those two large thick white wires that go to and from the coil connector to the pcb. Then post this or these picks IF you think you can't tell.
Hard Nosed