CMOS Low Battery - what could be the reason?

Question

Batteries

Hello!
I reset the BIOS with a jumper - I got what I wanted, only now the PC does not turn on without a second reset (the fans just spin). After the next reset, it is written that CMOS Low battery.
This problem is definitely not with the battery: I have tried three, and the last one is just off the store shelf.
BIOS updated - nothing changed. I rearranged the RAM sticks, leaving only one - everything is the same.
Reset and without a jumper - the result has not changed.
Has anyone encountered such a misunderstanding?