HRM PRO Wrong HR data (very low) after battery replacement

Hello, I recently replaced the battery in my HRM PRO (2 yo) for the first time. I use it only for running (no swimming). The watch has notified me that the battery is low, but I ignored it for two runs because I run for 20-30 minutes, and I was planning to replace it later. But during those two runs, I noticed significantly lower HR data, so I decided to replace it immediately.

With a new battery, I have experienced the same or maybe even worse behavior. I have tried to replace the battery one more time, but it is the same.

Is there some hope, or is the HRM PRO gone?

Fenix 7S SS 16.22

HRM PRO 8.8