My 20 years brother died without much knowledge about Islam and he was not doing namaz (salah). However, he was very kind, helpful and good human being. What will happen to him? Will he be punished by God?
As stated in Surah Al Asar(https://quran.com/103/3?translations=20) the basic requirements for successfully entring jannah are:
1. To have Faith means to be muslim
2. Good Deeds
3. Keep reminding each other of Akhirah
4. Have patience in this life as it is a test
These 4 things are required to pass the test of life.
As for salah, it is very important part of Muslim's faith. But its one of the good deeds as mentioned in 2 point. It is a fard. And its Allahs right that he can forgive someone who do not preform salah. Allah will forgive every sin except shirk. Allah will not forgive a human right util the human forgives it. And salah is not a human right its totally Allah's. He may punish for it or forgive it. But as for you brother he was a Muslim he will InshaAllah go to Jannah finally. You should pray for your brother that Allah may forgive your brother for not preforming salah.
May Allah forgive us all.