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Lenovo Legion 5 (15ITH6H) kind of boot loop but not sure

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    Lenovo Legion 5 (15ITH6H) kind of boot loop but not sure

    Hi, I wonder if anyone can help me fix my Lenovo Legion 5 (15ITH6H) laptop. Basically, after a windows update the computer would not boot anymore. When powering on the laptop the screen has no backlight and nothing would show up, using an external monitor did not help. However, the laptop would still spin up the fans and turn on the keyboard backlight. The keyboard backlight intensity function key would work and the power button led and the charging led are also working. I've tried every possible combination of key press and power button hold down time but did not change anything. At this point it looks to me like a bad bios. I then bought a CH341 programmer, disconnected the batteries and proceeded to flash the bios (version h1cn58ww) on the 8mb and 16mb ICs, I've tested the diff between the bin file read from the flashed chip and the bin from the downloaded bios and they match.

    However, now when attempting to power up the computer, there is no screen, no fan and no keyboard backlight anymore. The only thing that happens is that the power button led would turn on for 5-10 seconds than turn off for another 10 seconds and loop between led on and led off. During the loop, If i press the power button when the led is off, it then turns on and stays on without looping. The charging led turns on when i connect the power supply. I've tried to remove the ram, remove the SSD, re-flash the bios. I even tried to rollback to the original bios to see if i could revert to the situation were at least i had the fan and keyboard backlight working, but to no avail. It looks like some sort of boot loop thing going on but I don't know for sure and would not know what to do next. The computer is a couple of years old and out of warranty. I noticed there is a third IC chip of 2mb in size that perhaps need to be flashed, but i guess it has nothing to do with the bios as the bios is composed by 2 files of 8 and 16mb in size.

    Does anyone have any idea or suggestion on what to try next?

    Thanks, I appreciate your help.

    #2
    Mention the mb markings and link schematic/bdv for better response.

    Since its almost dead now, you need to probe from scratch.

    What are the rails that come up for the brief seconds when power on led is glowing?

    If the mb is amd platform, then bios chip is 1.8V and not 3.3V

    Comment


      #3
      Hi, please find attached a picture with the mobo markings (NM-D711 rev 1.0) and the schematics. Unfortunately I´m quite inexperienced with electronics, can you provide some instructions on how to test the power rails? The mobo is Intel and the bios chips are 3.3V in fact i was able to flash them with a known working bios but the problem persists.
      Thanks!
      Attached Files

      Comment


        #4
        https://www.badcaps.net/forum/troubl...equest-15ith6h

        Boardview and Schematic

        Comment


          #5
          With the help of boardview and schematic, you can locate all the coils(PLXXX).

          Measure resistance to GND(black probe to Ground, red on coil).Meter set to 20K scale.
          You need to lower meter scale to 200 ohms for measuring coils near cpu/gpu/pch.
          This should be done with no battery/adapter attached.

          Next set your meter to dc voltage range and measure the voltage on coils.
          Share your readings.

          PS: This is gaming mb and quite expensive. My suggestion is to get it repaired from an experienced technician if you dont have good experience in this field.
          The unit may get damaged beyond repair with even a slight mistake.
          However, this suggestion is not to discourage you and /or undermine your capabiities.

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