Sophos XG86w, Hardware Problem, forget the cmos settings, System Status (red)

Good evening,
I got an old Sophos XG86w that is out of support, the status LED often shows an error (red).
Otherwise it is running properly so far.

This also happens in the BIOS, i.e. OS has not yet started,
so the BIOS of the XG86w seems to find an error.
But it also often happens that the status LED shows nothing.

According to the Sophos manual, the SSD is defective,
but the MMC Health Status of the Sandisk MMC shows.

eMMC Life Time Estimation A (0x01) - The disk has used 0%-10% of its estimated life time
eMMC Life Time Estimation B (0x02) - The disk has used 10%-20% of its estimated life time
eMMC Pre EOL information (0x01) - Normal: consumed less than 80% of the reserved blocks.

In addition, the XG86w tends to forget the BIOS settings as well as the date and time.
The CMOS battery is fine, and the power supply to the double Schottky diode shows no abnormalities.

Even after a reboot with correct settings, the settings are lost.

Has the problem already occurred with one or the other and has a solution been found?

An RMA of the hardware is excluded, so support will not offer any assistance.

FreeBSD or OpenWRT runs fine on the XG86w without any problems.

Is there a BIOS update for the XG86w?

Core version 5.12
Compliancy UEFI 2.5; PI 1.4
Build Date and Time 12/03/2018 15:16:41

Or the Sandisk MMC ?

eMMC F/W: 73103517