Strange case of potentially corrupted BIOS - EliteBook 8540p turns on and off endlessly

[Sheikyon]

I am a computer scientist and electronic technician. I received an HP EliteBook 8540p. The owner acquired it reconditioned, thence components such as the mechanical hard drive disk or the RAM memory cards are completely new.

The laptop turns off three or five seconds after being turned on, and it does so continuously at irregular second intervals. There is no display, no beeps or sounds. The mechanical hard drive disk can be heard working during the few seconds that the computer is on before making a sound indicating the sudden loss of power, which means there is continuity to the mechanical hard drive disk.

It is strange to know that the owner reported to me that the problem occurred just after resetting the BIOS settings to default values and that, when it was restarted, after having confirmed the restoration of the BIOS values to the default ones, the laptop began to turn on and off endlessly, holding hands with a completely black screen, making evident that the screen is not even on. Whether he is strategically avoiding certain information or not, I created a bootable USB with the latest BIOS version of the HP EliteBook 8540p (68CVD family) and tried to boot the computer using the Windows + B key combination and even added the V key to the formula, and in spite of it didn't turn off and eventually — after 30 seconds or so — the fans turned on and the LEDs stayed on, there is no display on the screen. There is no video output through an external monitor (two VGA cables have been tested, both new and almost unused).

I tried other versions of the BIOS. From the oldest (2010) to the newest (2015), which included making variations with the folder structure and file system as well as the name of the .bin that contained the BIOS and the adjacent files necessary to perform the recovery, but got the same result: no display, but no reboots.

At this point, it is important to highlight that the mechanical hard drive disk, in contrast to the previous case, is not read and the corresponding LED that indicates its reading and writing is not on. This, perhaps, is an indication that the USB memory is detected and the laptop has attempted to boot from it accordingly.

The following was tested for the sake of the resolution and exclusion of possible causes:

-  The 8 GB of RAM memory [2 x 4 GB] was exchanged between the 2 available slots in 2 combinations. By leaving one of two modules, two exchanges were made between the slots. 
- The mechanical hard drive disk (HDD) was removed.

- The CMOS battery was removed and even replaced.

- Tried to turn it on with the battery removed.

- Peripherals such as the keyboard, screen, touchpad, certain flexible flat cables, and network adapters were removed in search of short circuits or false shutdown signals.

- The condition of the electrical capacitors was tested.

- Power and voltage levels were checked with an HP BIOS Recovery USB inserted. (the USB port receives power and the USB memory has the LED on.)

- An attempt was made to turn on the laptop from the board using jump-starting.

At the moment and given the circumstances, I consider the possibility of not only corruption of the BIOS (in this case I would extract it for manual reprogramming), but also the integrated circuit that contains it. The replacement will not be expensive, however, I am asking here given the strangeness of the problem the device is experiencing, and the unexpected circumstances that led the laptop to the unusable state in which it is today. It has been through 4 technicians beforehand, and none of them were able to bring it back to life.

Ergo, I ask, does anyone have any idea what could be happening to it?

Update: It appears that the computer's BIOS was strangely corrupted (reason for this: unknown).

I prepared my soldering and heat station for removal with the object of reprogram and rewrite the F.60 version of the BIOS making use of the EZP2019 accessory, although I could have perfectly used the ch341a. The computer now starts; there are no on-off loops or black screens. Notwithstanding, it remains curious that a simple reset of the BIOS configuration done from the BIOS itself has triggered such a problem. I have chosen to reduce it to a bug, a pretty serious one to be honest.

[erico]

"The owner acquired it reconditioned, thence components such as the mechanical hard drive disk or the RAM memory cards are completely new."

That is an unfortunate generalization. 

The system board still has time on it and cannot  be reconditioned. It has between 10 and 12 years since it was manufactured.

The Windows + B key  + power key combination is meant to try to effect a BIOS recovery.

It requires holding down the Windows + the B keys after pressing the power button, for up to a minute to see if the BIOS will respond by providing a BIOS recovering message and recover to its previous state. 

" HP BIOS Recovery USB" does not provide a check of voltage levels.

If you want to put some time into the laptop, it is time to use your multimeter and esr meter.

Check for the voltage rails starting at the charge port and find out why the 3.3v for memory and perhaps the 1.2 vdc for the processor are possibly not present.

[Sheikyon]

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" HP BIOS Recovery USB" does not provide a check of voltage levels.

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That is not what I asserted. I asserted that I conducted power and voltage tests — using a voltmeter — with a HP BIOS recovery USB inserted (read about recovering the BIOS through a USB flash drive), because at that point, the computer does not turn off and I am allowed to understand what causes it to be that even with the fan on and the RAM having continuity there is no display.

That being so, I already ruled out that it was a power/voltage problem, which are frequently manifested by blinking on the power LED on HP laptops (8 when it was tested with an when it was tested erroneously, and not by me, with a Dell AC adapter with input with 100-240 V - 1.5 A and an output of 19.5 V - 4.62 A, in contrast with the input of 100-240 V - 1.7 A and the 18.5 - 3.5 A with 65 W output of the HP supplied cable).

The points I covered seek to elucidate, not directly, how unlikely it is that in a restart a component or a integrated circuit could be compromised. Restart that was not even done by the owner of the laptop but by the BIOS when it was determined to reset its configuration to the default values. It seems that it has not been the only case, and I can attach this other report.

And the BIOS of the laptop was obtained from the official HP website, here.

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That is an unfortunate generalization. 

That cannot be a generalization since it was not asserted that the motherboard was reconditioned but that certain components such as the motherboard or the mechanical hard drive disk were.