Power off your phone >> press side key + volume down key together >> you will enter into safe mode & check if the phone is working fine and restart the phone
the same problem im facing in my phone im purchased it in sep2020 but yesterday suddenly the screen black out now samsung person told mee change your screen of rs 7000/- because its broken from inside because of pocket pressure, how rubbish my phone is still original with not any single scratch on it but they told its broken from inside, bad product, please not purchased it
Try reflashing your device. If it doesn't work (most likely), then it's a motherboard issue.
By the way, all Samsung Galaxy M30s devices are defective and are prone to these issues.
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