820-01598 5V 0.26A

Cant find any liquid.

When charger connected to one port got 5V and 0.25A.
On another port got 5V 0.24A and the USB C multimeter turns of and then turns on in cycles every 5 seconds.

Checked diode mode readings with USBC meter and all looks fine.

Replaced U3100 which is linked with not stable port but still the same issue.

Any idea where to start?

Restarting means board tries to start; the other port seems to have problems.

Check diode mode to ground on all big coils and other secondary power rails.
Don't forget SSD power rails.

Did you test with good battery connected?

It turned on with known good battery.
I tried to flash U2890 but IC was not detected with IC reader.
I used IC from donor board and flashed with 'original data'.

Got 20V on both ports but wont boot.

Checked voltages on the page where it shows boot sequence and all power lines are OK.

Got Apple logo but fan on max rpms.
Veery laggy in 'hardware test' cant load it after enter password to wifi, very slow - almost frozen trackpad cursor.

Did 'revive device' in DFU but same issue.

Tested with another top case and the same issue.
(stays at Apple logo and fan on max)

Is the battery charging now?
You may get this symptom if battery is not properly detected.

Yes, battery is charging.
Checked voltage on PPBUS_G3H and it going up.

Check SMC_AVREF voltage.

SMC_AVREF 1.24V

Test starting in safe mode.

Any error pops up starting in diagnostic mode?

All sorted - my "known good" top case was faulty - tested with another one and all works fine.
So in that case U2890 failed which has been replaced and flashed

Many thanks for help.