Many customers have reported that switching the AHCI mode to 'Enabled' in the BIOS can fix the boot device problem. The BIOS menu differs significantly between manufacturers, so consult your motherboard's documentation for specific instructions. As a result, there is no one-size-fits-all strategy to discuss this troubleshooting process.

In general, though, the procedure is pressing the Delete, Escape, or Function keys while the computer is booting up to access the BIOS. After that, go to Advanced Options and look for Set AHCI Mode. Change the value of AHCI Mode to Enabled. I hope that this solution helps to fix inaccessible boot device error in window 10