Question Laptop won't POST, turns on and off by itself ?

[Joe465]

Hi, hope you can help with my issue

So, my laptop HP Probook 4540s was working perfectly fine until like 2 weeks ago. That day I had an issue when I plugged the AC adapter and the LED that is on top of the ac jack flashed white, the pc turned on but the battery wasnt charging. I looked it up online and solved it by hard reseting by pressing the power button 15 secs without the AC adapter plugged or the battery.

After that I had no problems until 4 days ago.

This time I was using my laptop as usual in the morning and then hibernated it and went to get food, when I came back I tried to turn on the laptop but I couldn't, when I pressed the power button the only thing it did was that the power button light up, the fan sounded like it was spinning at full speed, the screen was pitch black, no post and after 5-10 secs it shut off. If I tried to to hard reset and nothing. The weird thing is if I left the pc alone after several hours and tried to turn it on, it worked properly but if I hibernated it or shut it off the problem appeared again.

I looked online and I saw in forums that it could be:
1. The laptop was overheating, that could explain why it shut off by itself and why it worked after leaving it and trying hours after
or
2. The BIOS was corrupted and registering a wrong temperature.

So I opened the pc, I dusted it off, removed the heatsink and cleaned it, reapplied thermal paste to the CPU and graphic card, also I disconnected the CMOS battery for 5 min to reset the BIOS.
I then put the laptop together and to my surprise when I connected the battery or plugged the AC adapter, the pc turned on by itself but now the fan didnt spin, the screen was black/no post, the power button LED lighted on, the HDD led blinked but very dim. Again after 5-10 secs it shut off by itself but instantly turning back on, stuck in a cycle.
One thing I noticed is that the fan was trying to move but it couldnt, like it was also "blinking".
I tried hard reseting but nothing.

I'll appreciate any help.

 

[Lutfij]

Welcome to the forums, newcomer!

HP Probook 4540s
ac jack flashed white, the pc turned on but the battery wasnt charging
solved it by hard reseting by pressing the power button 15 secs without the AC adapter plugged or the battery
That would be an indication that the battery on your laptop needs replacing or the AC adapter might be deteriorating or you're having a grounding issue, considering how disassembling the laptop will discharge any and or all residual power on the motherboard. Is your laptop on the latest BIOS version?

 

[Joe465]

Welcome to the forums, newcomer!

HP Probook 4540s
ac jack flashed white, the pc turned on but the battery wasnt charging
solved it by hard reseting by pressing the power button 15 secs without the AC adapter plugged or the battery
That would be an indication that the battery on your laptop needs replacing or the AC adapter might be deteriorating or you're having a grounding issue, considering how disassembling the laptop will discharge any and or all residual power on the motherboard. Is your laptop on the latest BIOS version?

Thanks for replying.
I tested the ac adapter with a multimeter and gave the normal parameters stated on the adapter.
In the casé of the battery, even when I try to boot it with only the AC I couldnt get it to post, it just cycles. As for he BIOS, I reseted to factory settings it while doing the cleaning and thermal paste change.
Idk if this can matter but Ive upgraded the ram in the laptop from 1x4gb to 2x8gb DDR3 1333 GHz, this was 2 years ago and had no issue at all

 

[Lutfij]

Did you inspect the motherboard for any burnt componentry?

Idk if this can matter but Ive upgraded the ram in the laptop from 1x4gb to 2x8gb DDR3 1333 GHz, this was 2 years ago and had no issue at all
Possible, the laptop in question was only able to get 2x4GB without any hiccups, going higher would mean your chipset would be running hot...and as such I think you might've burnt a component on the motherboard. You could prove me wrong by swapping memory sticks with another kit/stick of ram.