Tank 3 pro batteryfirmare issue

Good day! 

Igot my TANK 3 PRO at novemer 2024 via OZON marketplace and engoyed it untill last week. Charge start acting funny. long charge, didn’t charge higher then 7 or sometimes 20 %(on original charger and cable), shuts down in random moments. I try AccuBattery and some similar programs tat show that current charge was 0 

I contcact seller via marketplace

https://www.ozon.ru/seller/unihertz-mobile-1206517/?miniapp=seller_1206517

and got drivers, firmware adnt tools. I susessfully uptate the firmware, turn on the phone, discharge it ang set for charge again(in unpowered state). There was constant 1% os charge so i live it be for a day. Now my phone  won’t turn on and show 0% or dont show anything an all.