note at end of this procedure you need to restart mac with network connected, holding down Command R to boot from internet. Then select Disk Utility to Erase/format disk. Following that reboot again using Command R and select Time machine to recover from. Works so seamlessly.
The thermal sensor cable has just two wires, grey and black. Grey face top and black face bottom of my screen. Or grey is closest to SATA Connector. my new Seagate SSHD connector has 4 pins and different connector so could not connect thermal sensor cable due to size difference. However easily cut piece off cable connector to fit(with mini hacksaw holding with pliers). Instruction says if multiple pins the grey should be close to SATA connector. This did not work for me. google the correct connector cable for your new drive and you will see where the black and grey wires should connect to. Mine are the two pins furthest from SATA connector. Black bottom and grey top again. You don’t need to buy the new/correct cable! This whole procedure has worked a treat and my 2010 mac is now incredible fast. Thanks so much!