HP EliteBook 835 G9 corrupted SIO - how to reflash?

[pingaroon]

Serial: 5CG2271DC5

Hello folks, have an 835 G9 Laptop, which started with keyboard lighting up, but black screen, no further. Tried changing the 2 bios chips (both 32MB WSON) with multiple various dumps but no result (coudn't find any 835 G9 dumps, but 845 G9 and 865 G9 use the same bios according to HP) Board voltages all appear normal. Long-pressing the power button has no effect, so suspect corrupt contents of the SIO (NPCX998HA0BX), assuming the chip itself is good. So, how to reprogram? Would soldering on a blank replacement self-program (assuming original bios chip contents are back on the board), or would modding the contents of the main bios chip to put it in mpm mode enable the existing SIO to be reprogrammed? Trying to avoid having to remove the SIO if at all possible. Have attached the original main bios and ec bios dumps. Any help appreciated. Thanks.

[peste]

Serial: 5CG2271DC5

Hello folks, have an 835 G9 Laptop, which started with keyboard lighting up, but black screen, no further. Tried changing the 2 bios chips (both 32MB WSON) with multiple various dumps but no result (coudn't find any 835 G9 dumps, but 845 G9 and 865 G9 use the same bios according to HP) Board voltages all appear normal. Long-pressing the power button has no effect, so suspect corrupt contents of the SIO (NPCX998HA0BX), assuming the chip itself is good. So, how to reprogram? Would soldering on a blank replacement self-program (assuming original bios chip contents are back on the board), or would modding the contents of the main bios chip to put it in mpm mode enable the existing SIO to be reprogrammed? Trying to avoid having to remove the SIO if at all possible. Have attached the original main bios and ec bios dumps. Any help appreciated. Thanks.

The SIO chip can only be programmed when it is empty and at the first start....either erase the contents of the SIO chip with a programmer, or change the SIO chip with a new one...remember...not all HP models have the chip programmed itself......ideally you would have an adapter for the chip and programmer, write the new external chip in the adapter then solder the chip...as a last resort if you can't find a bios for this laptop model you can try with a new chip to see if it writes it...don't forget to make a copy of the SIO chip before writing....I don't know if this chip can be written with the programmer via the keyboard...

[pingaroon]

Thanks peste . It's a pesky BGA SIO, so I don't have the equipment to program it externally. I have a Successor programmer and a TL866II+ but there is no record of anyone programming a NPCX998HA0BX either through the keyboard connector, or via JTAG (and the absence of any schematic stops the possibility of programming via JTAG). I'll reflash the original bios chips and put a new, empty NPCX998HA0BX chip on and see if it manages to self-program... Will report back once the chip arrives from China...

The SIO chip can only be programmed when it is empty and at the first start....either erase the contents of the SIO chip with a programmer, or change the SIO chip with a new one...remember...not all HP models have the chip programmed itself......ideally you would have an adapter for the chip and programmer, write the new external chip in the adapter then solder the chip...as a last resort if you can't find a bios for this laptop model you can try with a new chip to see if it writes it...don't forget to make a copy of the SIO chip before writing....I don't know if this chip can be written with the programmer via the keyboard...