I have a Maytag MDB6601AWW Dishwasher. The #3 light next to Heat Dry is on. Pressing any other button only results in a flashing L and #3 light 5 times. I understand that this means the control panel

SOURCE: Kitchenaid dishwasher - door will not latch

The latch needs to be replaced. Kitchen Aid has made two updates to this latch. I.E. 2-revised latches. I just replacd the latch assembly and the dishwasher works fine now. Do a search for kitchen aid repair parts online and hav them shipped to your home. The repair takes five minutes. Un-screw all torx bit screws on door and the latch is under neath. One electrical dip switch held on by another screw and a two prong tab to undo the old latch. This seriously took me five minutes to repair and the parts were $40.00 online shipped.

Hope his helps.

SOURCE: Kenmore dishwasher Lock On light flashing

holding the button for four seconds will not do it, you have to hold it until the light stops blinking and
will go back to normal, normall takes more than four seconds to unlock the unit, this is something
the sears repair techs know becouse the are trained on all this things but, they will not share this things, becouse thats how they make money

SOURCE: Won't start. Light on next to "heated dry" button & "#3" graphic

You have the lock activated. press and hold the HEATED DRY button for 3 seconds

SOURCE: control panel lights blinking

I have the same dishwasher with the same problem, try pushing the delay/resume button, then the drain/off button. When the lights go off start your wash cycle.

SOURCE: my maytag 200 quiet series dishwasher has a button

The control panel has bee locked. Press and hold the heated dry button for 3 seconds until the light next to the lock "3" button goes off. This feature is to prevent small children from starting it. Locking the controls works the same way, hold the heated dry button for 3 seconds will turn it back on.