How To Fix Turns Off Issue?

Hi all,
I have Nokia 8 phone, which had purchase in October 2020. After purchase, he works nicely but after two months it turn off (Randomly). It won’t even restart, just turns off.
Specification
– Operating System – Android 7.1.
– Processor – Qualcomm MSM8998 Snapdragon 835.
– Battery – 3090 mAh.
Any tip or any suggestion before calling Nokia Customer Care?
Thanks