Got the dreaded 8.8… unplugged overnight then reconnected, mashed the start button and it tuned over, stopped, and 8.8. returned. Pulled the board and the four 820 resistors in the UR corner are scorched-looking. Assuming that maybe just some condensation might have caused a short since the unit is in a semi-heated area and its bee very cold here but w/high humidity and that a quick board swap will do the trick but need to somehow confirm so as not to blow up another board. Comments?
Here are your parts
http://www.appliancepartspros.com/partsearch/modelsearch.aspx?model=MDE5500AYW
Cannot be very helpful but can at least supply you with some info.
http://www.servicematters.com/maytag_library/docs/16023110.pdf
Try running the diagnostics.
I do not have a schematic for the board but you could try tracing back the resistors and then check that component.
The discoloration may be normal, I do not know. Hopefully someone with more experience will jump in and help out.
8 looks like a keypad problem. Check it with a meter.
You could try the following but it is a long shot as the error is a stuck key not an open key.
Connector Cleaning / Checking
Unplug the unit
Open it up
Remove the ribbon cable from the keypad to the control board at the control board.
Clean the edge connector.
If it is the type where there is not a connector just the insulation is removed, it can be cleaned with a pencil eraser. Do not use an ink eraser as it is too abrasive.
Check the tracks in the ribbon cable for hairline cracks. A magnifying glass helps here.
Would not hurt to clean the connector on the board. Use electronics contact cleaner or isopropyl alcohol and a tooth brush. Be gentle and do not reconnect till all the solvent evaporates.
Reconnect everything and give it a try.
I would check the heater relay AP4037260. I have seen these short out before, but not on this model. Also, I use a non-residue contact cleaner available at Radio Shack.
ok.
rad the pad check and came up w/some screwy stuff:
-pins 10 + 13 DNF
-pins 9+13 are the "time +"
-pins 12 + 14 DNF
-there is no pin #19 for the "damp dry"so thinking it might be #16 instead, tried it, DNF
-pins 11 + 15 are actually the "prevent" instead of "release" but do sem to operate "release" a bit…
The rest tested out ok
I metered the 820 resistors and they all check out +_ 5%
I notice that the top of the 16v cap is pooched up a bit and the hot melt is no longer attached to the board.
How do I check the Heater Relay?
If your capacitor is bulged out, your board is probably bad, an ac short to the capacitor will make it boil out liquids.
The relay I saw had shorted 230 volts to the coil and blew out the pc board. Just check the coil resistance.
I see…
You mean the heater coil?
Could condensation have caused the AC short somewhere? Its been very cold here in NW Ga but with 77% + humidity and the unit is out in the "summer kitchen". The windows there have been so full of condensate that sash is getting moldy…
No,I am saying the little coil inside the heater relay may have arcted over to the 230 volt contacts. If so, the coil inside the plastic cover of the relay may be blown open, just check.
Neither of the relays show any visible damage.
I have an older RatShack digital multimeter. Can I use it to check the cap and the relays?
You can check the relay coil but not the cap. There is evidence the cap vented steam so your board is bad and the relay suspect.
rad the pad check and came up w/some screwy stuff:
-pins 10 + 13 DNF
-pins 9+13 are the "time +"
-pins 12 + 14 DNF
-there is no pin #19 for the "damp dry"so thinking it might be #16 instead, tried it, DNF
-pins 11 + 15 are actually the "prevent" instead of "release" but do sem to operate "release" a bit…
Ya lost me
What is DNF?
As richappy said your bulged capacitor does indicate that the board is toast.
DNF=Does Not Function
I get that the board is toast but before I part with $100+ I want to try to isolate what caused the failure so as not to cook another one.$$'s tight these days.
I am not an EE but after a half century on this rock I’ve come to expect that catastrophic failures are just little failures snowballed 
If it is at all possible I’d like to identify what that little failure was…
All I can suggest is that you check all the parts that the board runs with a meter.
Odds are it is just the capacitor that went south.
Electrolytic capacitors are infamous for problems of this sort.
I did some checking around and looks like low voltage at the unit can also cause this.