About to Toss a Brew (High Mash temp)

... for the first time ever.

A few weeks back I brewed an AG German Wheat and mashed way too high. I was targeting 153-154, but because I was distracted with several other things I didn't notice that the temp was actually around 163-164. Normally I check, stir and recheck a couple times to ensure the temp hasn't crept, but in this case, I mashed-in and left for an hour. When I returned I saw the temp was 162 (I lose about 1-2 degrees an hour on warm days.) I checked for conversion and it appeared complete, so I finished my boil + additions, cooled and pitched. Fermentation was fast starting and vigorous, but finished in 2 days. I checked the FG and it was near my target but surprisingly a little low.

I assumed it would be a little sweeter and full bodied, but instead it's dryer and astringent. I racked to secondary and let it sit another ten days. The astringency is less, but frankly it still tastes like crap. It's thin and astringent.

Today, I'm either going to dump it or put it in the garage for a few weeks and see if it improves.

Any thoughts?

Gelatin works great for removing astringency.

I think typically a high mash temp will create more unfermentable sugars. Since you hit your FG then I would say that end of it is all right. The astringent taste might be tannins from the high mash temp, but I was under the impression you needed 170 or so to really extract them.
Maybe sit on it a few weeks and see what happens.

I will look into gelatin as a possible solution, thanks.
Whitehause, I was assuming the same thing, that's why I'm confused by what I'm tasting. Instead of sweeter and fuller-bodied, it's thin and astringent.
I didn't dump it (yet) so I may try cold crashing it and/or trying the gelatin. I haven't quit yet.

I did the same thing with a SMaSH brew, walked away and the temp crept up to 180! It tasted like crap the first couple weeks in the keg but it mellowed out big time around the 4th week. I killed the keg and my bro in law and father in law really liked it. My wife couldn't drink it but I didn't care, more beer for me.