I did this on a 2009 white unibody Macbook with a caddy that fit well, but I couldn’t get the second hard drive to show up in Finder, DiskUtility, or with ‘diskutil list’ in Terminal. System Report’s SATA Device Tree does show two SATA connections possible, so it seems like all is good up until the connector.
The previous optical drive was '“broken” according to the owner of the computer, which I presumed was just classic optical drive breakage, but perhaps it is down to the connector between the two?
Any other guesses what might be wrong?
But apple is not gonna do the repair beyond the warranty, so I don't believe it's a consolation that apple would do that repair when I buy computers to last me a decade. You seem even a bit optimistic about this.
This guides information does NOT apply to Redmi Note 4 GLOBAL. I have the global and it looks different inside.