Lenovo Thinkpad E14 - FE4A0/FE5A0 NM-C421 REV 1.0 - stuck on 5V

[mon2]

ali.nb66 , try a bios upgrade from the vendor's website (Lenovo).

The power delivery controller requires firmware that is injected into the RTS5455 using the I2C pins during the bios reflashing process.

If this fails, you can consider the above ideas in the thread which is to source another RTS5455. This replacementcan originate from a donor board or a trusted vendor. In the above thread, one of the techs noted a good vendor that worked for them. The power delivery controller will be blank and then reflashed during the bios upgrade process.

OR

Search for 'NM-C421With program' on Aliexpress to source a controller WITH the program already onboard. This may be most practical. Be sure that the logic board is the same as the OP of this thread = NM-C421. Otherwise, hunt for the controller & firmware that matches your logic board.

If you proceed, update this thread with your progress for future readers.

[ali.nb66]

hi bro
can u fixed this problem???
i have sim sim your problem

[worldofskin]

All power removed, there is no short on the CCx lines or any other data lines i checked.
Diode mode - CC1 - 475mV
CC2 - 642mV
Many of the ESD TVS diodes are missing, in my understanding it doesnt really matter (it shouldnt stop the board from charging) - or am i wrong?

[mon2]

Remove all power and confirm the DIODE mode measurements for the CCx lines. Meter in diode mode. Red meter probe to ground. Black meter probe to pin to test on the USB Type C connector. Checking to see if perhaps a local ESD TVS diode is blown which will cause the BMC communication lines to fail and result in the power delivery contract stuck @ 5v.

Also review this thread:

https://www.badcaps.net/forum/troubl...-with-rts-5455

[worldofskin]

Hi guys! I have this board - NM-C421 - the board is fully functional but the charger -> usb c port - gives only 5V. Sometimes it takes 1.5A and without the battery the main powerful is on and up to spec. I replaced the rts5455 for a working one from other working board but still no luck. ps: the board originally came to me not working - I changed a few input mosfets and the battery switching one and now it works. Tho it's not charging as mentioned above. Any idea where to look? Thanks in advance!