16:9And men were scorched with fierce heat; and they blasphemed the name of God who has the power over these plagues; and they did not repent, so as to give Him glory.

And men were scorched with FIERCE HEAT;

The previous verse discussed the sun's heating capabilities. This is a FIERCE HEAT not a mere heat wave. Most likely this will exceed the air conditioning capacities and force people outdoors. This is only make matters worse and may explain the rest of this verse.

and

  1. THEY BLASPHEMED the NAME of GOD who has the POWER over these PLAGUES; and

    These people don't have the Helper (John 14:15-31). The "ruler of the world" (John 14:30) has come and the Antichrist has NOTHING in Jesus. So these people, Antichrist's followers, too, will have nothing in Jesus or God. Hence they BLASPHEME the NAME OF GOD!

  2. THEY DID NOT REPENT, so as to give HIM GLORY.

    These people can't bring themselves to admit that they are getting their just punishment for taking the mark of the beast. Furthermore, they feel POWERless because even their "ruler of the world" leader cannot turn down the HEAT.

    From a longer view, these people must be done away with in order for the prophesy in Isaiah 52:1-6 to become a reality. This bowl through the FIERCE HEAT of the sun is saying "Here I am.".

Glory to God only comes from a repentant and obedient heart. We believers, need help from Him who will make us stand in the presence of His GLORY (Jude 24-25). These people refuse to repent and will not stand in the presence of His GLORY but rather their knees will bow to Him (Isaiah 45:20-23-25).