ASUS Vivobook 14 OLED M3401QA not posting

[Luke11037]

Hello everyone,

I have an ASUS Vivobook 14 OLED M3401QA which is not posting. Currently when plugged into power/turned on the power indicator will illuminate and the battery indicator will flash white roughly once every 3 seconds. Leading up to this it would sometimes turn on and then other times not turn on, furthermore it also showed a screen saying "new cpu installed, fTPM/PSP NV corrupted or fTPM/PSP NV structure changed" and then a screen telling me to recover the bios however it is no longer even posting at this stage.

The diagnostics steps I have attempted is to flash a bios i got off here however this did not change anything. I have checked all major power rails and they are not shorted and have a good voltage reading. Attached to the post is an image showing the voltage (battery disconnected) and resistance to ground readings i took of the inductors on the board, in addition the board view i found for the board is linked here https://www.badcaps.net/forum/troubl...1000-boardview.

Im unsure what steps to take next in trying to fix/diagnose this laptop and would love any information or tips anyone has to offer.

Thanks all

[Luke11037]

Attached is a picture of the backside of the board and updated measurements i took to include the cpu power inductors

[reformatt]

Voltages etc look good. You have Vcore so it's either BIOS, memory or CPU related. Given it's an Asus, first thing I look at is build quality and flexion when the lid is opened/closed.

Repeated twisting of the board results in cracked solder balls under the CPU. I don't waste too much time on Asus laptops.

[Luke11037]

Voltages etc look good. You have Vcore so it's either BIOS, memory or CPU related. Given it's an Asus, first thing I look at is build quality and flexion when the lid is opened/closed.

Repeated twisting of the board results in cracked solder balls under the CPU. I don't waste too much time on Asus laptops.

Is there going to be any way to tell if its cpu or memory related as im pretty sure bios can be ruled out at this point?

Thank you for the information

[reformatt]

When the unit is fully assembled, open the lid from either the RH or LH side. Do you see any twisting or flexing of the palmrest? This is the most common thing I see on these thinner lappies these days.

First thing to try is to change tightening sequence on the CPU heatsink screws to see if that changes anything. I have applied some kind of weight on top of the CPU when the board is on the bench to see if it works etc. I usually look at the input current via the adaptor input to see if there is any variation during power on.

[Luke11037]

When the unit is fully assembled, open the lid from either the RH or LH side. Do you see any twisting or flexing of the palmrest? This is the most common thing I see on these thinner lappies these days.

First thing to try is to change tightening sequence on the CPU heatsink screws to see if that changes anything. I have applied some kind of weight on top of the CPU when the board is on the bench to see if it works etc. I usually look at the input current via the adaptor input to see if there is any variation during power on.

I dont see any twisting in the chassis or the board at all so im doubtful it being an issue caused by flexing/twisting of the board over time.

I did already consider this and tried it but made zero changes at all in behaviour. Temperature of the board also made zero difference in case the board could have only worked while hot or cold due to issues with the solder joints somewhere.

[reformatt]

Another common issue on Asus boards are the copper test pads corroding and going open circuit. Any that aren't shiny I examine under a scope or measure to make sure they aren't open circuit. Check all areas of the board closely for any corrosion, especially near the fan.

No other ideas other than checking input current from adaptor during boot sequence. Try pressing different areas of the board during power on to see if you get variations.

[Luke11037]

Another common issue on Asus boards are the copper test pads corroding and going open circuit. Any that aren't shiny I examine under a scope or measure to make sure they aren't open circuit. Check all areas of the board closely for any corrosion, especially near the fan.

No other ideas other than checking input current from adaptor during boot sequence. Try pressing different areas of the board during power on to see if you get variations.

That is one thing i did notice is the test pads arent shiny at all, loads of them are off colour or dull.

I have barrel jacks on order for my bench top power supply so will update when i got those in rather than just injecting 19v with probes at the dc in jack. Thanks for the suggestion

[reformatt]

I have an Acer on the bench right now with an AMD CPU where it's not issuing PM_SLP_S5#. When the board is pushed slightly near the CPU just above it, the board springs to life. No other damage, and the chassis doesn't appear to flex either.

Definitely a CPU contact issue. I am seeing this more and more on these latest gen boards.

[Luke11037]

I have an Acer on the bench right now with an AMD CPU where it's not issuing PM_SLP_S5#. When the board is pushed slightly near the CPU just above it, the board springs to life. No other damage, and the chassis doesn't appear to flex either.

Definitely a CPU contact issue. I am seeing this more and more on these latest gen boards.

Do you know anywhere i could find more information about lines like PM_SLP_S5# I could find and check across the board to see if im missing one of those lines? Im likely suspecting the same if its becoming a common theme among newer boards with how they are designed.

[johnbeton]

I have an Acer on the bench right now with an AMD CPU where it's not issuing PM_SLP_S5#. When the board is pushed slightly near the CPU just above it, the board springs to life. No other damage, and the chassis doesn't appear to flex either.

Definitely a CPU contact issue. I am seeing this more and more on these latest gen boards.

In that case you could try a reflow ?

[reformatt]

In that case you could try a reflow ?

My policy is to write these off and advise the customer to invest in a better laptop. Even if we were to reflow or reball, the fault will just re-occur down the track as we are really treating just the symptom, and not the cause. Even a motherboard replacement is not in the customers best interest as the chassis will still allow the board to flex, just by opening the lid!

[mcplslg123]

Agree to some extent.However, a proper reballing will extend the life of the unit for not less then a year.

[reformatt]

I don't agree.

You have to balance the amount of time this would take, your labour rates, the chance of success (CPU or PCB could warp), chance of the job bouncing due to laptop/PCB flexion and having to do a warranty repair or another reball for $0. You'll have to charge a fair amount for this and in Australia, most customers will decide to write off this kind of laptop in favour of a replacement (better quality or refurb) laptop.

On top of that, it was a kids school laptop. Kids are extremely rough with these, and Acer and Asus build quality simply is not suited to that kind of abuse. Chance of that repair bouncing is extremely high.

I did this repair for another computer shop. He reported that customer contacted Acer and stated that they will replace the board for just over AUD $200 (which is quite cheap, assumption they are doing a board exchange and sending the old one back to the factory). I charge a diagnostic fee, and never have to see the thing again.

[mcplslg123]

reformatt, we all agree to disagree and thats the beauty of this forum. I've reballed intel SOC(4th gen to 9th gen) on many many occassions. every other dell 3567 mb(15341-1) will come with SOC dry. The success ratio is close to 80% and none has come back within a year.
I dont reball SOC on motherboards which tends to warp even on a BGA station.

[Davi.p]

Probably bad contact on bga chips, how much is old this pc? Is it hardly used? Try eventually this test, put the main board in a paper/plastic bag in freezer for half an hour, remove it, mount it rapidly and test it, notice if is there any change/improvement, if any then bad BGA balls, the fact is that are all to be cured! Not only processor ones.. This is why the low rate of duration.. tell me if you can do it, i will tell you the trick for how can it last longer..