If after a hardware change and you encounter Error Code 0x803FABB8, Donor hardware ID does not own operating system entitlement, see this fix.

To fix the Windows 11 operating system wasn’t found error, run the Startup Repair Tool. To do so, boot your device using the Installation media.

My InsiderThe essay "I was accepted into my dream Ph.D. program but chose to join a startup instead. The company folded in a year" was removed because it didn't meet Business Insider's standards.

The essay "I was accepted into a well-regarded graduate program. I turned down the offer because AI is destroying my desired industry" was removed because it didn't meet Business Insider's standards.