Either you need to replace or flash the BIOS chip. As modern computers' BIOS chip is generally EEPROM, flashing would be fine. Flashing software is generally provided by manufacturer (check official website). You can also use universal flashing softwares like AwdFlash (Most Popular). Flashing is not that hard. Its a thing of double-click or single command. For example, -- to update BIOS (involves flashing) -- a novice Windows user could just downloads an exe file from manufacturer's website & run it.
You'll have to remove BIOS chip from motherboard & flash it using another PC with BIOS flashing hub interface (a kind of device used for connecting external BIOS). If you don't have that device, you can still use another PC for flashing: Just boot a PC & replace that PC's BIOS with your one (Hot Swapping) before executing flashing command. Then, flash it. Its a myth that -- for hot swap based flashing -- you should only use a motherboard of exactly same type (same chipset, same manufacturer etc.). In fact, you can use any motherboard as long as computer architecture is same (Probably, you shouldn't try inserting PC's BIOS in a Tablet).
If you don't have expertise of doing this, I'd recommend you to take your PC to service center of manufacturer.