On the Ford Mach E, which is basically Ford's copy of a Tesla, you can replace individual internal battery components. Here is one we have apart right now. One of the power modules/battery packs failed. These can be replaced in pairs once the battery is dropped from the vehicle and opened up. It involves whatever it costs to get 2 new power modules, and about $600 for 2 packs of thermally conductive glue to attach them to an internal cooling plate, plus labor charges. Before the new modules are installed you must look at some scan tool data of the other cells, then use a special balance charger to pre-charge the new modules to the same level as the others. It's really interesting inside the traction battery assembly, it contains the 12 power modules, an assembly of high voltage contactors, internal liquid cooling, a computer, and a few other things. Actually the fuse for the high voltage AC compressor is inside this unit too, so hope your ac compressor doesn't short out because you'll have to drop this battery and take it apart to replace that fuse. The individual power modules are heavy as fuck too, Ford sent all dealerships special brackets to use with an engine hoist for replacing them. And a special hydraulic lift table to remove and install the entire assembly from the vehicle.

By no means is this cheap, but it's a lot better than having to replace the entire battery assembly like apparently Tesla requires.

This particular one was bought back under the lemon law, and has been sitting apart for several weeks because the conductive glue is on back order.