MacBook Pro A2159 starts for 5 sec & off again

[mferna14]

Hi all, I am working on the Apple MacBook Pro A2159 Logic board # 820-01598-06. I removed the Logic board & it seems to be clean & no sign of liquid spill anywhere or any component. The problem is when I plug in the USB-C power adapter cable, It turns on, Voltage 20v & .42amp (Without the LCD Fex cable attached). And when I attached the LCD flex cable to the LB, I see the backlight for few sec which is very obvious, the amps on the amp meter keeps dropping to ZERO amp (In either case) & then the backlight disappears & restarts all over again. No image at all. But on one instance I saw the battery charge icon on the LCD screen when I did not plug in the USB-C cable. I checked the 3.3V which is perfect witout any errors & stable all over, but 5V is good for a while & the drops to 4.2v & restarts & back to 5V, which then turns on the logic board again, till this fluctuations happens once again. Any help or tips would be really helpful. Thanks in advance.

[mon2]

Re: MacBook Pro A2159 starts for 5 sec & off again

Hi. Check the resistance to ground of the 5 volt rail.

Check the current sense loop of the 5 volt rail to be sure no parts are missing. The local regulator for that rail may be incorrectly concluding there is a fault on this power rail due to the current sense circuit.

What are the voltages of the SDA and SCL lines on the battery connector?

[mferna14]

Re: MacBook Pro A2159 starts for 5 sec & off again

Thanks mon2., There does not seem to be short on the 5V power rail. The resistance is around 287K & keeps on geting low. & in this I see under the MS, no parts are missing.
Voltages of the SDA and SCL lines on the battery connector J6951, both are perfect 3.3 volts... I was checking Louis video on Youtube regarding this same problem, they even could not find teh fault, but I will try to sort it out. Any other tips??? Thanks