I don't know for sure, but it sounds like you ended up with something unexpected in your mix. It's possible something strange is growing in there.
Because of the blue coloring, it seems more likely that some unexpected compound is reacting with the copper parts. You mentioned the yeast you used tastes bad. Any chance it has the skunky or rotten egg taste like sulphur? Copper isn't usually very reactive, but it does react pretty readily with sulfur and some of the resulting compounds have a vibrant blue color and would taste awful.
Either way it's probably a bad idea to drink it.