That sounds like mold if it's black growing on the mycelium. If it's your first inoculation then don't be to worried, practice makes perfect. I just found a bunch of fuzzy black mold growing in a poppy pod I almost threw up just from wafting a smell of it, no kind of mold is something you want growing around your house. I'd probably just throw it out and boil the jar in hot water or soak it with some 90 proof isopropyl alcohol to hopefully remove any mold spores and make sure to open the jar outside and then take a shower and change cloths. To hopefully reduce the risk of further contamination. Note I've never grown mushrooms before and my information is only from researching and studying I did on the internet about it. I had everything I needed for a perfect BRF-Tek and then I went and lost my syringes and just said fuck it.