I had a 5 gallon pail of straight fermented 7 lbs LME to correct an over-hopped pale ale I have. My AC went tits up so the temp in the house went right through the roof. It went to 80 - 90 degrees for about two weeks indoors. The LME had finished its initial fermentation before this happened, but it seems to have developed a very fruity taste anyway. The overhopped brew was kept cool the whole time.
So I mixed the two anyway, because either this works or I need to free the kegs up in the next few weeks. I had a sample taste and the bitter brew does not mask the fruit. The question is whether this fruitiness is going to go away, or is it a lost cause?
If you can't fix it with a hammer, you've got an electrical problem.