ইলেকট্রিক ব্যাট দিয়ে মশা মারা কি জায়েজ?

Differentiation between burning with fire and burning with electricity is not accurate, the issue is one. Setting fire to firewood produces heat that causes a certain form of burning, and connecting to electricity produces heat that causes a certain form of burning. Hence, what applies to burning with fire applies to burning with electricity.

When you reviewed the killing of insects by burning them with electricity, you set the killing of the insect before its burning with electricity, when you said: "The reason for combustion is the running of electricity through the insect's body which generates heat...This heat causes the burning of the insect's body...Hence the insect dies from the electric force, not from combustion, since the combustion takes place after the death of the insect." Meaning that the insect is burned after it is already dead. This, my brother, might be a valid view, which needs a deeper study by the specialists. The insect was shocked with electricity and burned, and the insect was alive, not dead. When the insect was shocked with electricity, it became dead and burned. So why to say that the insect died of electrocution then burned through electricity after that? The insect was found dead and burned after it was electrocuted with the electric racquet. Therefore we need the opinion of experts as to the cause of death of an insects hit with an electric racquet: Is it burning through electricity? In such case, the texts pertaining to the prohibition of burning living things would apply. Or is it that the burning took place after the death of the insect? Based on this analysis of the underlying reality, a legal judgement can be passed.

The evidence on the prohibition of killing by burning is explicit. From this evidence is the following:

Al-Bukhaari reported from Abu Hurayrah (ra), who said: "The Messenger of Allah (saw) sent us on a mission and said: «إِنْ وَجَدْتُمْ فُلاَنًا وَفُلاَنًا فَأَحْرِقُوهُمَا بِالنَّارِ» "If you find so and so and so and so, then burn the two with fire." Then the Messenger of Allah (saw) said, when we were about to leave: «إِنِّي أَمَرْتُكُمْ أَنْ تُحْرِقُوا فُلاَنًا وَفُلاَنًا، وَإِنَّ النَّارَ لاَ يُعَذِّبُ بِهَا إِلَّا اللَّهُ، فَإِنْ وَجَدْتُمُوهُمَا فَاقْتُلُوهُمَا» "I commanded you that burn so and so and so and so, although no one punishes with fire except Allah. So if you find the two, then kill them."
And Ahmad reported in his Musnad from Abu Hurayrah (ra), who said: We were sent on a mission by the Messenger of Allah (saw), so he said:

إِنْ وَجَدْتُمْ فُلَانًا وَفُلَانًا لِرَجُلَيْنِ مِنْ قُرَيْشٍ فَأَحْرِقُوهُمَا بِالنَّارِ». ثُمَّ قَالَ رَسُولُ اللهِ حِينَ أَرَدْنَا الْخُرُوجَ: «إِنِّي كُنْتُ أَمَرْتُكُمْ أَنْ تُحْرِقُوا فُلَانًا وَفُلَانًا بِالنَّارِ، وَإِنَّ النَّارَ لَا يُعَذِّبُ بِهَا إِلَّا اللهُ عَزَّ وَجَلَّ، فَإِنْ وَجَدْتُمُوهُمَا فَاقْتُلُوهُمَا

"If you find so and so and so and so, the two men from the Quraish, then burn them with fire." Then the Messenger of Allah (saw) said, while we were about to leave: "I commanded you that to burn so and so and so and so with fire, but only Allah Almighty punishes with fire. So if you find the two, kill them."

Thus, burning animate beings with fire is Haram. The prohibition is general and not restricted to human beings, and therefore it encompasses every creature. The Hukm Shar'i is the prohibition of punishment or killing with fire and all that this comprises, such as punishment or killing with electricity.

As for the Hadeeth you mentioned and from which you understood that killing with fire and burning is Makruh (disliked) and not Haram (forbidden) through the indication of the term "I shall be ashamed of Allah", then this deduction is prevailed, because the Prophet (saw) said afterwards: «لَا يَنْبَغِي لِأَحَدٍ أَنْ يُعَذِّبَ بِعَذَابِ اللَّهِ» "It is not rightful for anyone to punish with the punishment of Allah."

This is the text of the Hadeeth:

Saeed Bin Mansoor reported in his Sunan from Ibn Abi Najih, who said: "The Messenger of Allah (saw) sent out a company and said: إِنْ وَجَدْتُمُوهُ فَاجْعَلُوهُ بَيْنَ حِزْمَتَيْ حَطَبٍ، ثُمَّ أَشْعِلُوا فِيهِ النَّارَ» ثُمَّ قَالَ: «إِنِّي لَأَسْتَحْيِي مِنَ اللَّهِ لَا يَنْبَغِي لِأَحَدٍ أَنْ يُعَذِّبَ بِعَذَابِ اللَّهِ..."If you find him, then place him between two packs of firewood, and then set him on fire." Then he (saw) said: "I shall be ashamed of Allah, it is not rightful for anyone to punish with the punishment of Allah..." End of Hadeeth.

So as you see, the Messenger of Allah (saw) after his saying «لَأَسْتَحْيِي مِنَ اللَّهِ» "I shall be ashamed of Allah" Said: «لَا يَنْبَغِي لِأَحَدٍ أَنْ يُعَذِّبَ بِعَذَابِ اللَّهِ» "It is not rightful for anyone to punish with the punishment of Allah."

If this is summed up with the Hadeeth of al-Bukhari, it becomes clear that punishment or killing with fire are Haram.

To put it in brief: The legal provision depends on the analysis of the underlying reality of killing with an electric racquet, to know whether it kills the insect through burning or whether the burning takes place after the shocking strike of the insect from which it dies, so after that the electricity runs through the insect's body and burns it. This needs further investigation by specialists, and based on this the legal provision is deduced.