I have never seen or used these before, YouTube is your friend. here is a video showing some tips https://youtu.be/svrUeZEg1MI
I looked it up as I wanted to know what this was...
Personally, I would never consider using one of these packs when there is absolutely nothing wrong with dumping yeast straight into the mash even without a starter. it been done ...
I would take a gravity reading and taste it!
it looks like it fermented well, did it come out of the top?
if you had the white cap on it then that is definitely OK. CO2 is heavier than air, so would have protected the beer, and your white cap would have stopped bigger bogies from getting in.
but all in the taste, right?