It's motherboard is damaged.
My m21 also has this problem and I changed the motherboard under replacement for free
Google this issue you will find
Many users had this problem.
This is the big issue
Samsung has betrayed it's budget customers
Many Galaxy m30s owner's devices became dead because this issue and they also had completed their warranty.
You will have to pay Rs 7000 for motherboard
Please read my name 🙂
It's sad that your smartphone is out of warranty
Now you will have to pay 7k for 1 year old smartphone 😞
My phone also got this problem after 6 months and luckily I changed the motherboard under warranty.
It used to restart automatically and stuck between samsung logo for 2 hours!
You have to change the motherboard for 7k in service center or straight upgrade the device... 😞
May your issue gets solved
You can ask more doubts freeely.
Also please read my name 🙂
For some users, it got fixed after factory reset.
For some users, it was fixed after Flashing new firmware.
For some users, it fixed after changing motherboard.
For some users it was fixed after next software update.
For some users, it is not fixed even after following the above tips.
But noone knows the exact solution for this issue.
Dear Samsung Member,
Greetings from Samsung Customer Support!
We acknowledge your query and apologize for the same. We request you to kindly visit the service center for a physical inspection of your device. You can locate your nearest service center with this given link: https://www.samsung.com/in/support/service-center/
Thank you for writing to Samsung.
Samsung Customer Support