OptiPlex 7080 SFF Core i7-10700 2.9Ghz - SSD 256 GB - 32GB

When I started the PC for the first time, the English-only UEFI greeted me with an error message. According to the error message, the time was not set correctly. I then set the time correctly. The PC then restarted several times. After several reboots, the Windows 11 setup screen appeared and the language was back in English. I therefore reinstalled a German-language Windows 11 Pro, freshly downloaded from the Microsoft website. The installation went smoothly. The above-mentioned error message due to an incorrectly set time came up again when I disconnected the PC from the power supply and reconnected it. The PC started automatically, although the "AC Recovery" function in the UEFI is set to "Power Off". My suspicion was a flat BIOS battery, but this cause of the error would be so simple that the "refurbisher" would certainly have noticed it - I thought. My voltmeter knew better. The installed BIOS battery was indeed flat. Since inserting a new BIOS battery, the error message due to an incorrectly set time no longer appeared. The PC also no longer starts automatically when it is reconnected to the mains.