If your bow is not grouping well, besides anything loose on the bow, try shooting and retrieving just one arrow. Even if it's a bad arrow, crossbows are machines and they will shoot pretty much the same hole every time with one arrow.
If you shoot and retrieve and shoot and retrieve that one arrow and it’s all over the target it's NOT the arrows, it's more than likely YOU. Every time you pull the trigger you’re pointing that bow in a different direction.
Adjust Your Technique
These new bows are their own animals. One bow is NOT going to shoot like another and you need to ADJUST YOUR TECHNIQUE to see what the new bow wants (and it’s probably different than your old bow), and once you find that technique, hold it. You can’t shoot a 12 gauge shot gun all your life, pick up an AR and knock eggs off golf tees at 500 yards without a bit of trigger time and some technique adjustment, why would a crossbow be any different?
I have proven time and again that the main reason a bow is “not accurate” or “will not group” is the shooter. Not the bow, not the arrows, but the shooter. Take your time, do the one arrow deal like I said and LEARN THE BOW before you try grouping arrows. If you can't drill bullet holes with one arrow something is wrong and don’t take yourself out of the variables, more than likely you're not shooting the bow how the bow wants to be shot.