lin, on the back of the instrument cluster is a printed circuit board that is prone to developing cracks in the solder joints. seems to be the same issue as other solder free connections:-) These micro cracks appear to be around a couple of resistors, of course this will lead to first intermittent failure, then to total failure. The instrument cluster board is around $300 but you may be able to fix it by resoldering the connections, basically a reflow of the board. Let us know if you are up to repairing it, so we can assist you more if needed. Hope this helps, good luck.
Part 2 of the question
1 At the same time the cooling system is serviced, all hoses and the radiator (pressure)
cap should be inspected, tested and replaced if faulty.
2 With the engine cold, remove the pressure cap and set the heater control to maximum heat.
3 Move a large container capable of holding at least 10 quarts under the radiator drain
fitting to catch the coolant mixture as it's drained.
4 Open the drain fitting located at the bottom of the radiator. On vehicles equipped with the V6 engine, the drain fitting cannot be reached by hand. To open the drain fitting, use a universal joint and socket attached to a long extension. Allow the coolant to completely drain out.
Remove the drain fitting and replace. You are looking for something like the attached image.