Internal hard drives not recognized - NOT the hard drive cable

Hi - I'm having this problem. I have an A1278 mid-2009 MacBook Pro, 13", 2.26 GHz. It's definitely not the drive (have tried 2 that I know function and 1 that was brand new). I replaced the hard drive cable twice (first was just the cable, seconds was the cable with the bracket so I know the cable is connected; it's the side cable and it had adhesive). I also reset the PRAM and SMC The llaptop does boot if I use the drives I mention before externally. As soon as I connect them internally, I get a flashing question mark folder. It doesn't boot in single user, verbose, or safe mode. When booting from the install disc or repair mode, the only drive recognized is the optical drive.

I added tape on the data side of the connector to ensure a good connection (no, pins are not occluded). I still get a flashing question mark folder. What's my next step?

Tell us about the hard drive. Samsung drives in particular have problems with older MacBooks and MacBook Pros.

If all else is good what operating system are you using? Boot from the DVD if Snow Leopard or earlier, or use Recovery Mode for OS X.7 and later.


https://support.apple.com/en-au/HT201314

I would suspect something is going on with the SATA cable or the connector to the logic board. I know you said you replaced the cable twice and the hard drives... You can boot with an external hard drive so we know the logic board is functioning. But that does not mean the connector is OK. I don't know what else it could be based on your description and troubleshooting.