It's no secret that the MacBook Pro with Retina display is a difficult machine to service. Now it turns out that Mac Geniuses and technicians at Apple-Authorized Service Providers need to take two special classes and pass an exam to be qualified to service the device.
As noted in a post on 512 Pixels, there are two self-guided online courses that are prerequisites to grabbing your pentalobe screwdriver and popping open the Retina MacBook Pro. The first is a general "MacBook Pro (Retina, Mid 2012) self-paced training course", while the second "Embedded Battery Safety self-paced training course" deals with the glued-in battery pack in the device.
The post includes a link to a take-apart guide for the newest MacBook Pro, which states that the non-removable battery is not a replaceable part, and that the entire top case assembly needs to be replaced to service a faulty battery. That guide also shows the location of ten Liquid Contact Indicators that are built into the Retina MBP; damage due to liquids isn't covered by the Apple warranty or AppleCare, and it appears that Apple's going to be very sure that your device hasn't gone for a swim before offering to repair it.