Laptop does not power on occassionally, no consistent behaviour

[Ballistica]

Hello, I purchased this laptop second-hand from a buisiness. It worked fine for a year, but now it appears to have strange issue.

Issue:

Seemingly at random, the laptop fails to power up, keyboard lights up, screen remains black, caps lock flashes continously (no pattern/beep code), no post or bios/nothing on screen, then the fan goes to 100%.

If I pull the battery/AC and shut it off, sometimes then it will boot nromally through BIOS and into windows, and run fine all day. The 'failure to boot' appears to be random and I can have 10 successful boots in a row one day or 10 failed the next day. There appears to be no way to make it consistently fail.

Testing:

- OCCT benchmarks/stress testing - Passes everything (if it makes it into windows)

- Reinstalled windows using windows 'rest' function (full reset)
- Battery life appears normal, works with battery out AC in, battery in AC in and on battery only.

- HP diagnostics tool in UEFI  - Passes everything

- Removed ssd - No change in behaviour

- Removed and swapped RAM sticks - No change in behaviour

- Rest BIOS by removing CMOS - No change in behvaiour

Testing I cannot do:

- I cannot access the BIOS, nor update it as I do not have the BIOS password (being a second hand laptop). This would be my next step.

Any ideas?

[Jupitero]

Hello.

About BIOS version - check the current version number and then the release notes for all the versions released ever since at the 9470m download page. Select Windows 7 as the operating system on the page to show all versions. (Selecting Windows 10 will only show updates from the moment HP qualified the system for Win10...)

Although the BIOS pw may be circumvented, it is a taboo subject on these boards these days, so look for that info elsewhere (or much older messages in this forum...)

While you are at it, check all the available firmware updates as well, should some of them apply to your machine. (probably no effect on the real problem at hand, though)

I roamed this forum for your problem and found a couple older cases with identical (?) problems on a 9470m:

- In a similar sounding case the laptop was repaired/replaced.

- The outcome was inconclusive in this one...

Your laptop consists of many different modules - not everyone of them is critical to start the laptop. Follow the Maintenance and Service Guide for 9470m and remove/disconnect everything except system board and memory. Connect an external display and keyboard to the unit to exclude the internal one in any way of causing the problem.

Should you still have problems starting the laptop - and you have tried with known working memory modules as well - the system board is faulty and needs to be replaced. The same guide lists all possible system boards with their respective product numbers. Whether they are available or have a reasonable price I cannot say. You can always look out for used 9470m laptops with e.g. broken screen to scavenge the board.

[Ballistica]

Thank you I will try your suggestions