Also: Display getauscht und originalen Homebutton mitgetauscht, aber Touch ID geht nicht mehr (Homebutton drücken geht aber): Nimm die Metallplatte hinten vom alten Display ab (6 oder 7 kleine Schrauben, nix kompliziertes), da ist das Homenbuttonkabel angeklebt dran. Dein iPhone nochmal öffnen, Display abnehmen, die Metallplatte samt Kabel austauschen und alles wieder sehr vorsichtig zusammenbauen. Nichts ziehen, knicken oder würgen. Zur Sicherheit hier bei ifixit nochmal nach dem Tutorial “home button replacement” oder “Display wechseln” schauen. Gute Chancen dass es jetzt wieder funktioniert (neues Display + alter Homebutton + altes Metalshield). Hintergrund: die Replacement Displays (alles keine Apple Originale) scheinen bei diesen Kabeln anscheinend billige Qualität zu verbauen. Hoffe das hilft!

Had the same problem twice: Macbbok Pro died without warning while surfing on battery, and did not start at all any more. Only the above mentioned SMC bypass helped as a temporary fix. Problem that fans are on high speed, battery not recognized nor charging, and sleep doesn't work anymore, since the SMC is bypassed during startup and controller does not get any infos on battery, temperature and the like. Doing an SMC reset afterwards put the laptop again in dead mode. I got around with ordering a new "Left I/O board" or "DC-In board", installed it and voila: everything's fine. One month later computer died again with same issue and the same process: surfing the web on battery. Go figure. Ordering the next I/O board from ebay, installed it, but did not work this time. Afraid that I ordered a broken one. Again got stucked with the SMC bypass option. I did read about the 85W power supply, but negleted it since I was sure to have the correct one. I have 3 Macbooks around in the house, and replaced a lot of...