failure to post on power cycle or restart on motherboard

[Massivesiege]

hello

i have a dell xps 13 9533 laptop that acts in a very peculiar way , the laptop fails to post, when the power button is depressed, it  turns on and enter a black screen with keyboard back light and the lcd back light lit , but doesn't initiate any kind of post there is no dell logo on the display , it just lights up the keyboard back light and the lcd back light and remains turned on , with the cpu heat sink getting warm,it remains on  indefinitely until the soft power button is depressed long enough to force shut it off ..

the ram and cpu and gpu are all soldered on so , i cannot reset anything physically,  i unplugged the battery and plugged it back and it behaves the same way , but when i unplug the battery and remove the rtc cmos battery and then try powering it on , it boots fine ,i even ran the dell diagnostic on the bios that checks the ram and cpu and chipset  for fault and all the self test  was successful , it even uses the speakers to beep 5 times to indicate that the rtc cmos battery is unplugged

i can boot into windows or linux and use it with no problems but as soon i command a restart it shuts itself off (doesn't restart) and when you try powering it on via the soft power button it resumes the earlier behavior of no post no boot just light up leds , until i unplug the cmos battery again and drain any existing static charge on the motherboard with the battery removed

to summarize
1) once the motherboard posts and the bios chainloads the operating system, the unit boots into the operating system with no issues and functions with no problems , until a restart is command within the operating system , where the unit proceeds to shut itself down,not the intended function of restarting, it seems like the handoff of the operating system to the bios where the bios is responsible for the boot process again with chainloading the operating system fail in some way and the laptop just shuts down , it seems to fail at the bios initialize (post) period or the hand off period of the bios by the operating system i am not certain , but to stress when a restart is commanded in the operating system it shuts down

2) following this shutdown state , when the soft power button is depressed the unit doesn't post at all , it lights up the lcd backlight and the keyboard back light , and the cpu heat sink is observed to getting warm to the touch , it will remain in this turned on position until the soft button is depressed long enough to command a force shutdown, normal post procedure will not resume untill the rtc cmos battery is unplugged with the remaining static charge on the motherboard discharged , following which it post and boots properly all the way into the operating system until a restart or shutdown is commanded , note again a restart never work , it just shuts the unit down and enter the non responsive state previously described



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[Samogon]

Did you check if cmos backup battery is ok? if it is short?

[Electro Detective]

Did you check if cmos backup battery is ok? if it is short?

I've seen CMOS batteries short and come alive again.
twice I have had them go reverse polarity,
don't ask me how that's possible, 
ask both my multimeters, they told the story 

[Massivesiege]

hello

Did you check if cmos backup battery is ok? if it is short?

I've seen CMOS batteries short and come alive again.
twice I have had them go reverse polarity,
don't ask me how that's possible, 
ask both my multimeters, they told the story 

Did you check if cmos backup battery is ok? if it is short?

hello

thanks for the reply , i checked voltage on the battery the cell is not short , it is also not reverse polarity as well , the issue is very weird to say the least

i found the schematic of the motherboard , took some googling but turns out all the motherboard for big brands are made by a company called quanta computers and they sell the schematic of the motherboards , these are sold on various sites , i found an upload by someone on this site however

http://kythuatphancung.vn/uploads/download/04f94_Quanta_D13_Spyder_13.3+DA0D13MBCD1_UMA+1013+1730_cost_DELL+XPS+L321X.pdf

i am looking into acpi power states currently , from what i read acpi doesn't have a specific state for restart , its just does a normal shutdown but pulls reset on all the chips so that it bootstraps again , as these units are soft start this is entirely possible

i am all ears if anyone has a better idea ,after googling the unit is famous for coil whine sound , not sure if it can be faulty inductor doing this

thanks for the replies much appreciated

[Samogon]

just for shits and giggles, try to update firmware.

[Electro Detective]

just for shits and giggles, try to update firmware.

Second vote for Firmware Update 

[Rasz]

and check with different ram module
but googling it seems to be this models design defect

[Electro Detective]

Firmware Update may address the ram issue

You won't know if you don't give it a go