Samsung — Faulty software update causing phone to turn ON OFF repeatedly.

My Samsung M31 8GB RAM 128GB ROM, was working great up until recent August. I updated my phone's software and after that my phone started facing this issue of constant on and off cycle automatically.
It is really tiresome and saddening as we spend a lot of time and hard earned money on shortlisting and buying a new phone, with great reputation in Market as of Samsung, thinking we will be free from any worries and tension regarding our phone for atleast a good period of time, but then this issue occurs.. and it has not been 1.5 years yet from the date of purchase..
Kindly help me with this issue.. as it is because of a software update I'm facing this issue.. i would really hope that this problem will get fixed without costing me any charges as the damage was from the company's side because of the faulty software update that caused this problem..