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Last night I downloaded the BIOS update setup sp57752 - HP Notebook System BIOS Update for my HP Probook 4520s laptop.. During the installation, when the software was displaying something like writing block 400 / 640.. the power malfunctioned and the laptop turned off.. (The battery was very low and my UPS was not working).. Anyways, right then I knew the laptop was bricked. I restarted the laptop and this is what happens..

  • The display stays off.
  • The CAPSLOCK key light keeps blinking.
  • The power button doesnt do anything, even if held down for 30 seconds or more. The only way to power off is to disconnect the battery and the charging cable.

I know I'd most probably need to take the laptop to HP customer care.. But I was wondering if there was ANYTHING I could do myself to fix this issue.. I know how to disassemble the laptop.. I know how to take out the RTC battery.. I wanna know if it'll be sufficient.. Or will it require special hardware cables / serial ports / etc and proprietry procedures that only an HP technician will be able to perform..

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Taking out the RTC battery which powers the RealTimeClock will not help. If you have an identical laptop and the chips are socketed then you can boot the other laptop, swap BIOS chips, and reflash the currently bricked one. I have done this once before on a desktop motherboard (Asus P2B Dual). On a laptop things tend to be soldered down so you are probably not that lucky. – Hennes Feb 14 '13 at 7:50
@Hennes.. this ill try this though.. it sounds interesting.. but im afraid of the same thing.. if things are soldered down.. but is it not unsafe? hotplugging the BIOS chip in and out of a running system? – AweSIM Feb 15 '13 at 5:33
If things are soldered down (and I bet they are in a laptop) then it will not work. If it is socketed then all I can say is that googling back then told me it can work, and I know it has worked at least once with (now) 12 year old motherboard. Note that a service center will either swap the motherboard (safe but expensive) or do something with JTAG or other tricks which the average users does not have in his or her house. – Hennes Feb 15 '13 at 7:55
thanks a lot mate.. id admit i was afraid that might be the answer.. if you can copy paste these comments as an answer, id be happy to accept them as the correct answer.. – AweSIM Feb 15 '13 at 12:26
up vote 0 down vote accepted

Taking out the RTC battery which powers the RealTimeClock will not help. That battery powers the real time clock and the volatile part of the BIOS. The BIOS program itself is stored in non-volatile storage.

When that gets corrupted you have a few options:

  1. Be the lucky owner with a rescue BIOS option. Intel did this a while. Their BIOS was split in two parts, the first part allowed minimal booting from a floppy and updating the BIOS. The second part contained the rest. Most upgrades only changed the second part, so you could recover if that went wrong.
  2. Be the lucky owner of a board with two BIOS chips. Sometimes one if a rescue version. Sometimes they are two full versions and you can select which one to use. There are only a few motherboards which use this, as well as a few graphical cards.
  3. Be the owner of two identical motherboards and have a socketed BIOS chip. That allows you to boot the identical computer (the one with the working BIOS). After it is booted an the BIOS is not in use (or copied to shadow RAM) you can carefully remove the chip and replace it with the EEPROM with the broken BIOS program. Then flash that chip. I have done that once before, but that was on a desktop board (Asus P2B-Ds, pentium-2 era).
    It is unlikely that a chip on a laptop motherboard is socketed, since space is at a premium.
  4. You might be able to program the BIOS using a JTAG interface. The hardware for that is not hard to come by, but you will need board specific knowledge. This is possibly how a repair technician will fix your board.

    (Or more likely, he will just swap the motherboard with a new working one and ship the broken one back to HP, who might refurbish it after repairing it that way.)
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thank you so much for that elaborate answer =) – AweSIM Feb 16 '13 at 0:00

The LED will likely be blinking a specific pattern. HP suggests the following

Identify the number of blinks or beeps

When there is a start-up problem and you see LED lights on the keyboard blink a few times (between 1 and 8 blinks), or hear a series of beep tones (between 1 and 6 tones), do the following actions. There is very little you can do to resolve blink or beep code messages until you contact an HP Support Agent or authorized HP Service center.

Recognize Blink Codes

With the development of the Extensible Firmware Interface (EFI) environment, the HP Pavilion and Compaq Presario notebook computers built in 2009 or later use blinking LEDS to identify hardware component reporting an error during startup. The codes are not valid for other models.

1.Press the power button to turn on the computer, and look for blinking LED lights on the keyboard.

2.Count the number of blinks in the sequence (between1 and 8 blinks).

After the sequence of blinks or beeps, there is a pause for a few seconds, and the sequence is repeated (usually 3 or 4 times). The blink sequence can be repeated by pressing the power button again.

Recognize Beep Tone Codes

On older computer models, the startup hardware diagnostic tests used a series of tones (beeps) to identify the error codes. Blink codes and beep tone codes have a similar purpose but do not indicate the same error conditions. The meaning of the number of tones in a sequence and duration of the individual beep tones is specific to the individual models. There were fewer beep codes on older computers because there were fewer built-in diagnostics.

Component Tested Error Condition

LEDs blink 1 time CPU CPU not functional

LEDs blink 2 times BIOS BIOS corruption failure

LEDs blink 3 times Memory Module error not functional

LEDs blink 4 times Graphics Graphics controller not functional

LEDs blink 5 times System board General system board failure

LEDs blink 6 times BIOS BIOS authentication failure

More info HP Error Codes

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