Tempered glass can shatter if it incurs stress point damage, large temperature changes, from impact, etc. Things like overtightening/removing panels screws can create stress cracks, and handling it at a later time can shatter the glass. There is also the less common possibility of NiS impurities in the glass. Depending on the situation, there might be coverage for the panel. If the case arrived with the tempered glass panel already broken, please contact the vendor and request an exchange, as that is likely a result of mishandling during logistics.