Many faults occur due to a dead battery.. and what may seem like a serious problem with computers may simply be replacement of the BIOS/CMOS battery!
All types of computers have a small battery, referred to as the BIOS or CMOS battery. This retains BIOS settings in the CMOS (Complimentary Metal-Oxide Semiconductor) memory chip. If the battery is low on voltage or dead, those settings will be reset to default when power input is lost to the system.
The battery is only a backup for when no AC mains or other power source feeds the circuitry. The average life of that battery is 3 to 4 years, depending on use.
The typical battery is referred to as a "coin cell", commonly the CR2032 model. Other types are used, perhaps smaller in size, as in laptops or 'smart' phones.
Check the owner's manual for the location and type of battery. Get a new one, and replace the old battery. Then go through all the BIOS pages to ensure the settings concur with how the system is built.