Sorry to say, but status code 07 is not good. Combined with the initial issue - sporadic no-boot-device-detected - it indicates the hard drive is dying.
You should double check your cables and connections: try a different SATA port, try a different power connector, and retest. A long shot - but maybe.
There is a possibility that a complete wipe of the hard drive (with a utility that writes all 0's across the disk) and a fresh, full format might correct the issues. Then you would need to reinstall Windows and all your programs and user data. If you wish to invest the time to give it a try it might be worth it. Just be sure to have those backups of your data up to date. If the drive is indeed failing it will very likely give it up during those very intense procedures.
But my best advise would be to start shopping for a new hard drive.