P14s Gen 2 AMD; no boot, no image, no backlight, no charge

[koriwi]

Hi guys, I am new here, but I've tried my best to read up on the beginner guides and reading some other threads. So here the base information i can provide.

-Lenovo P14s Gen 2 AMD
-Ryzen 7 5850u
-16GB soldered (32GB stick added, removed for debugging)
-256GB SKHynix SSD (removed and swapped for debugging)
-NM-D451 Motherboard (P/N: 5B21C82277)
-S/N: PF-34N64A
-Model: 21A0-000QGE

History and symptoms:
I had this Laptop for some time but stopped using it (installed Linux, worked perfectly) as I changed company and got a MacBook Pro (needed for iOS stuff).
After 2 years or so i wanted to use it again and install it as a dedicated windows machine for some special purposes.
I tried to boot it, obviously didnt work as the battery was empty. Plugged in the charger, orange LED lights up, but while I had it plugged it and tried to create my windows USB on this machine with Linux, I realized it is not charging (after some googling i had the impression that this and similar models have problems with bios updates and the battery).
I planned to run the BIOS and Battery controller update (or whatever it was) when windows was installed.
I didnt get this far, as while i had the windows installer running the screen got black. No image, no backlight. I waited for a relatively long time as i was watching a movie while doing this. But as nothing happened, i force restarted the laptop. It continued to show the same symptoms.
When pressing the power button, the following things happen:
- power button lights up
- Keyboard lights up
- F1, F4, Caps Lock lights up
- All keyboard lights/indicators turn off
- Fan spins up
- CPU gets warm
- Fan spins down
- nothing changes for a few minutes
- GOTO Keyboard lights up (repeat indefinetly)

I tried all kinds of things afterwards.
- pressing the reset button through the hole
- disconnecting battery (which is still empty) and BIOS battery
- removing extra ram
- removing ssd

Nothing changed at all. With a PD analyzer i can see that it always draws between 4-10W (spikes to 10W for 1s after boot)

I thought I probably have the same problem as many people -> bios corrupted (but i didnt do a bios update, maybe windows does it automagically?)
So i backed up the ROM of UB1 with FLASHROM through JBIOS1. Tried to flash a new bios which I got from the lenovo updater and extracted with UEFITool NE alpha 69.
This didn't change anything.

Any help is appreciated

[koriwi]

Please forgive me for bumping, but this post was probably invisible as i was still unverified.

[koriwi]

I hope somebody can help me soon and that my case it not super special.
maybe the onboard RAM is defective? I've read that there is the possibility of a BIOS mod to disable the soldered RAM.
I will now research on how to mod the UEFI and then reflash it as the symptoms for soldered RAM failure online more or less matched my symptopms

[pc_okay]

Hello,

You can try to post your bios in bios section and ask for a good known bios.

You can use boardview to mesure and post value of: (with power and system powered on, BE CAREFUL !)
APU_PWRGD
PLT_RST#
DDR4_A_DRAMRST#
DDR4_B_DRAMRST#
APU_RST#

If you have an oscillioscope check : (with power and system powered on, BE CAREFUL !)
LPC_FRAME#
YC1

Good luck.

[koriwi]

Hello,

You can try to post your bios in bios section and ask for a good known bios.

You can use boardview to mesure and post value of: (with power and system powered on, BE CAREFUL !)
APU_PWRGD
PLT_RST#
DDR4_A_DRAMRST#
DDR4_B_DRAMRST#
APU_RST#

If you have an oscillioscope check : (with power and system powered on, BE CAREFUL !)
LPC_FRAME#
YC1

Good luck.

Thanks for you answer!
Luckily i can do all 3 things you suggested as i have a backup of the original flash contents and i have an oscilloscope!
Trying it ASAP

Edit:
The boardview i have is a pdf and very hard to read with my browser. should i just use a dedicated pdf viewer or am i missing something else?

[pc_okay]

I just post the openBV version for you:
https://www.badcaps.net/forum/troubl...c-or-boardview

Good luck.

ps: yes PDF is a pain to search !

[koriwi]

Thank you so much!
Works like a charm

[koriwi]

Hello,

You can try to post your bios in bios section and ask for a good known bios.

You can use boardview to mesure and post value of: (with power and system powered on, BE CAREFUL !)
APU_PWRGD
PLT_RST#
DDR4_A_DRAMRST#
DDR4_B_DRAMRST#
APU_RST#

If you have an oscillioscope check : (with power and system powered on, BE CAREFUL !)
LPC_FRAME#
YC1

Good luck.

APU_RST# is at 1.81V (for a very long time directly from fan spin, didnt sit there with my probes to wait until it resets)
All other values are at what they are supposed to be (interpreting # as is supposed to be 0V)

I also attached 3 pictures.
Picture 1: LPC_FRAME#
Picture 2: YC pin 1
Picture 3: YC pin 3

Edit: The picture order is reversed. check the file names to see which image i am refering to.

[pc_okay]

Sorry but RST# signals are a Little confusing.
RST# signal should not stay enable (low state) for a long Time, they have to rise up immediatly after resetiing what they have to.

There is a # to say « reset active position is low » but signal can't stay in reset position.
Mb chip just need a fast reset not a continous reset, just like when you press a power/reset button, you don't press the button for an hour or you computer Will restart continuously

So your results are weird, APU_RST# is ok but other signals at 0v are not, double Check please.
Crystal is ok (YC1). 😊

[koriwi]

I tripple checked. it is all in permanent reset .
i've read that it's possible that it was not only a bios update that happened, but also an EC update. The p14s should have a selfhealing bios which fixes broken bios updates. i've found multiple known working bioses on the internet and tried all of them. didn't change anything.
But if the ec update was interrupted, there is no way around reflashing it, right? i've also read a special flasher is needed.