Old Extract or Over-carbonation or Infection = My Sour beer???

[Beerzilla]

Can anyone diagnose this?

I made an extract beer last spring with Black Rock Miners Stout extract that turned out a quite sour/cidery.

This particular can was found in my closet and 2 or 3 years past it's best-by date.

Unfortunately I didn't keep records so I can't give exact details of the brew.

I know:

The can was 2-3 years old.

Dunno EXACTLY how much priming sugar I added but I'd say it was in the area of 3/4 cup.

Fermented at around 22-24C (72-75F)

I used Safale S-04 and corn sugar.

A few friends described an interesting "blueberry flavor"

Bottle doesn't gush but there is a big head after pouring

At first, I thought the cider flavor was because it was still young, but now it's been half a year and the flavor hasn't improved. I'd say it's a bit more sour than before. I'm probably gonna toss it but I just want to know what went wrong? Was over-carbonation responsible for the sour flavor? Was the extract too old?? Or was it an infection?

Thoughts?

 

[StophJS]

Is that 72-75 ambient or actual ferment temp? 75 is the warmest recommended ferment temp for S-04, so warmer might account for the blueberry flavor. Oddly enough, I had a New Holland Poet (stout) on tap the other day at Peppino's and it had a very distinct berry-like flavor as well. It was really the only major flavor in the beer..