A few weeks ago, I purchased a Samsung Galaxy m30s. All was going very well until Sunday morning when it would not switch on. I know it is fully charged, because I had charged it that night. I have also tried the force restart buttons (power button and down volume) many times. Samsung customer care are not taking phone calls due to the covid crisis, and will not respond to any of my emails or messages. I am looking for the quickest way to solve this issue. The phone is only about 6 or 7 weeks old.
The above link explains how to Soft Reboot which i think you've done. It also shows how to hard reset but beware this will probably delete your information from the phone.
In the Uk all the Samsung Experience Store / Samsung Service Centres are temporarily closed due to the COVID-19 pandemic and I'm assuming the Samsung Callcentres will have staff self isolating or working from home so responses can be delayed im afraid.