What is the meaning of "Sanverim"?
Rashi #1 and Targum Yonasan: It means 'blindness'. 1
Rashi #2 and Targum Onkelos: It is a sort of bewilderment
See Peirush Yonasan.
How could they continue searching for the door to Lot's house, even after they had been smitten with blindness? How come they did not relent?
Seforno: There are some Resha'im whose wickedness is so ingrained that they can never relent. 1
As the Gemara says in Eruvin (19a) 'Even at the entrance to Gehinom, Resha'im do not to Teshuvah!'
How could they blind the people? This is like a second mission!
Moshav Zekenim: This was needed to save Lot, so it is like one mission. 1