Chosen Solution
I had an accident with my MacBook, someone spilled a tiny amount of liquid in it (just around the circuitry of high side current sense U5410). It has now been cleaned up with rubbing alcohol, but at the time of the spill the user kept using the machine. When I plug in the charger, the fan runs full speed (without having to press the power button), but no picture on either LCD or external monitor. Battery was completely drained (and will not charge). Tried with a fresh battery, but the computer won’t start when pressing the power button. Also tried SMC and PRAM reset, no luck. No chime when powering. I’ve identified a damaged component and maybe a trace. Pins 4 and 5 in the U5410 (INA214 current sense) is completely missing (burned up), so the INA214 must be replaced. Also, when testing for continuity between the pads of pin 4 and 5 it is open. I figured it should read 0.003 (R sense). Am I mistaken with the continuity? Also, based on my description (fans full blast when charger inserted, dead with only battery), will replacing the INA214 and the trace fix the problem, or does it sound like some other components must be replaced too?
Are you measuring continuity on U5410 with the damaged component still there? If so, remove the component first, then check continuity, since it could be bringing these pins to ground. I haven’t got a working board in front of me at the moment, but the donor board had an open line between these pins too (I have taken loads of components from this though). High side sensing can prevent it from booting, from what I have seen it can cause the mouse to lag if U5400/U5410 is bad. Replace U5410, run a wire for the damaged trace (if necessary) then check it out. I guess high side current sensing could prevent it from booting from battery, but I’m not entirely sure to be honest, so it’s best to replace it first. It’s an easy job, good luck! If the component has a marking on it, make sure the new one is in the same orientation as the original as well!
