Mid-2012/Early-2013 A1398 820-3332 MacBook Pro 15" dGPU GPU bypass.
This video will show You how to disable Your failed nVidia GPU on Mid-2012/Early-2013 15" MacBook Pro Retina. However in most cases all You need to do on this model is retouch U8900 chip with leaded solder, so try that first! If that will not do - try to reflow VRAM. If both above solutions will not fix Your problem - try this method.
After this repair Your brightness will be set at 100% at all times (can be controlled via Brightness Slider app available on the App Store). Also external monitor would not work.
I tried enabling native brightness control in the second part of the video but it was a flop. If You know how to make it happen - I would appreciate Your input! Thank You for watching!