So the Redmi Note 2 is really easy to take apart. I figured I don't have any warranty left on the device so I may as well open her up and see if I can spot the issue with the speaker why it refuses to work.
12 screws to get the rear frame off and another two more with a bunch of connectors to get the mainboard out. The speaker has two brass spring connectors that link it to the mainboard and they are taut and make good contact with the board. I slightly widened them in the hope that perhaps one was having an intermittent connection but alas, after reassembly the earpiece still does not work. I am currently scouting eBay for speakers to see if I can get it fixed or make it work again, at least as a backup phone once I get my Note 4
EDIT: After a second reassembly after I heard a femtosecond of speech come through the earpiece while testing I discovered the problem - there is a minute wire going from the speaker assembly to the voice coil and the one pole had disconnected itself from the solder pad. I had to use a magnifying glass to see the strand, so thin it was so there is no way I will be getting it back to where it is supposed to be. I found an eBay seller willing to sell me two pieces for $6, so I will order one and hope for the best