At this point Logic-Board figures will be checked by reading each affected and not affected component using schematic view of the PCB, failed components will be exchanged and re-soldered and then all the original remaining system parts are treated and cleaned and then reassembled. Once a system is reassembled a full system stress test and Apple diagnostic tests are conducted to ensure any intermittent issues are identified.
Its rare but it can happen that a fault can occur even after going through the full process. Its important to note that rescuing a system from liquid intrusion takes careful and dedicated technical work which takes time to complete. Some faults which only involve a small amount of liquid can be resolved with only the service.
Other systems will need to have some or all parts replaced. I/O Board, Keyboard, Track Pad, Battery, etc can all sometimes need to be replaced.