My guess is those 2 problems are not related. I would guess the flash problem is a bad stalk switch (I think there is a better name). There have been several threads about those switches going bad. Mine has been fine luckily although it always felt kind of cheap.

On the defroster, That draws a lot of current so even a partially bad connection will cause it to not work. If you can test the voltage at the window connections, both with them connected and also disconnected that will give you some info. For example if you get good voltage when they are disconnected but no voltage when they are connected then there is a bad connection or relay in the path from the battery to the window. On the other hand if you get good voltage when they are connected then the problem is the window element or connections immediately to it. And if you never get any voltage then the relay is not getting the signal to turn on or there is a completely bad connection somewhere.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra