Chosen Solution
History. MacBook Pro acquired with fault, flashing folder on boot up - will only boot from original 500MB hard drive in external caddy via USB. When connected to internal SATA cable HDD is not detected by OS. Action. Purchase logic board to SATA HDD cable twice - neither of which made any difference. Purchase SATA 3 120GB SSD, install as primary drive - not detected. Clone new SSD into boot disk put in USB caddy - OS detects external SSD and boots up. Replace DVD drive on MBP with caddy - install original 500 GB HDD as secondary drive and SSD in primary drive - neither are detected by OS. Run ADS from OS (logic board diagnosis) result was no problems found. Overview. Not faulty SATA ribbon cable. Not faulty HDD or SSD. Logic board appears to be working (flashing folder detected and ADS diagnosis). Any thoughts?
Fact that you see the flashing folder does not imply that the hard disk I/O is working, it shows up anyways. It seems all testing you’ve done hints only to a fault in the logic board unfortunately, no other explanation left that I can think of.
What does Disk Utility show you when you boot up under an external drive with either the HDD or SSD connected in the HD bay? If it doesn’t show up then I would inspect the logic board HD SATA connector. If it does then you may have been lucky to get two bad cables or you may have damaged them in the process of installing them.
