Diagnosing a non charging HP EliteBook x360 1030 G3

[touchatout]

I am attempting to diagnose a non charging HP EliteBook 1030 G3 and have a working one for comparison.
Being an experienced computer technician, this does not make me an electronic technician, so that I would really appreciate some help for the electronic part of diagnosing this laptop.

As a picture is worth a thousand words, I attach one, with annotations of some measured voltages.
I also attach three zoomed pictures from the healthy laptop, taken through one ocular of the stereomicroscope.
(I make these pictures copyleft ; feel free to edit/anotate them if it can help.)

I measured different voltages when the power USB-C plug was in each of the two available sockets.

As we can see, on the non charging laptop, when plug is in the left socket (hinges side), the voltage through the condenser located between the two ports is 4.97 VDC instead of 14.92 VDC.  (~10V difference)
When the plug is in the socket on the right (battery side), the voltage through the TVS fuse and condenser located on the right is 20 VDC instead of 14.92 VDC. (~5V difference).

The voltages at the pins of the Winbond chip are almost identical for the two boards, but those at the pins of the MXIC chip are very different.

---- Additional information (less useful) ---

On the defective laptop, the voltage measured at the battery pins when the battery is disconnected is 0.46V.
(When the battery is connected, it it thus of the battery, around 7.7V.)

On the healthy laptop, the voltage measured at the battery pins is between 8.22V and 8.54V, depending on how much the battery was charged.

The problem initially occured short time after replacement of the USB 3.0 port, which was done carefully.
The laptop was still working again and launched an BIOS / Firmware upgrade without my agreement.
During the BIOS upgrade is a unpgrade of the USB-C firmware. It has possibly be interrupted because this model of laptop show almost no sign of life during the upgrade of its firmware modules (screen remains black ; maybe the almost visible diodes on the power button, or a small orange diode on the keyboard (F11 key?) or at the Caps key are the only sign of life.
So, I cannot totally exlude a firmware corruption problem. However, I suspect an electronic problem first.

The battery itself has been drained, but could be recharged with another laptop and was delivering 8,16V after this.
The laptop has once briefly started (screen remained black, but fans spinning fast), when the battery was at 8.16V at the time when I removed the charging plug. After the fans were spinning really fast during around 1 minute, the voltage delivered by the battery dropped to 7.67V (below expected 7.7V). The defective laptop doesn't start again.
The laptop was also unable to start with an healthy battery.


(I wanted do display the images inline, and with the overview first, but it does not work.)

[BeBuLamar]

I think the computer has a BMS (battery management system) which control the chanrging of the battery and this circuit is bad.

[touchatout]

I also do think that the computer has a BMS.

I could not find a BMS chip as spare part.
However, the MXIC chip, at which the voltages are wrong, is sold as BIOS chip.
Maybe does this chip also ensure the battery management. Not sure if it is possibly dead or parts of the BIOS are corrupted.

Prior to a possible replacement of the MXIC chip, I think I should still further test cheaper components like protective diode / capacitors / resistors.

My multimeter is a Fluke 70 series II and has an Ohmmeter and a Diode tester.

For the ceramic capacitors, would an ESR meter be required ?

[MathWizard]

So does it run anymore from the power-brick with a barrel jack plug ? What voltage was that ? Those winbond and MX chips are just flash memory, they probably aren't rated for over 5V, so they are probably not being powered for some reason.

These types of things will usually have a start-up routine. So like higher voltages rails like 12V or 5V would startup, then output some "powergood" signal, that tells the next rail, like 3.3V, to startup. Then at the end the CPU and ram/etc start running.

Since you worked on that USB port, are you absolutely sure there's no solder bridges, or conductive residue left on the PCB ? I killed a few op-amps a while back, from using strong flux, that leaves a residue (alcohol never cleaned it enough, and the flux got under the chips, and under the edges of pads)

It might be worth a try just to remove that thing again, and see if it works off the powerbrick then ?

As for the startup order, the charger chip should be 1 of the very 1st chips, and if it had a problem, that would stop the sequence. It's a nightmare to find where traces go on these, but I'd try and map out the power rails, just from the plug in, and then to any power IC's that are linear regulators, or DC-DC converter chips. A fair amount of them should have datasheets online (they do for PC parts).

See what voltages are on their Vcc, enable pins and powergood pins. To really see the order of things, you would need an oscilloscope.

I've never worked on a battery charger circuit, but I can imagine the little knot of logic circuitry for making it shutdown, when something goes wrong. If you're lucky, it is shutting itself down, and it wasn't some run away problem.