Matebook X Pro, no display, auto shutdown after 20 seconds
I've got a huawei matebook x pro which was handed over by a friend that asks me to check and test if everything still working except for the screen, he said he dropped the laptop and there's no display, I can see a small crack on bottom left corner of the lcd. He was ready to buy a new lcd but the thing is Im not even sure if the problem is actually just the LCD. or if the LCD is actually dead or not
Here's what I found about it.
1. If I press the power button. it will turn on (keyboard lights, fan spin, usb port has power) and stays on for about 20 seconds but no display, then after about 18-20 seconds it automatically shuts down. I can confirm its off by checking some voltage on the board like GPU, CPU and RAM voltage.
2. If I press the power button, then clicks on the touchpad (or external mouse connected via USB/USB-C port) it will stays on and will never autoshutdown, but still no display. It seems like if it detects a click event during boot, the laptop will stays on until I turn it off.
3. While the laptop is on. I notice that sometimes if I hit F10 then ENTER, the laptop will restart, then I have to do a clicks again so it won't auto shutdown. and I can do these process over and over again (it seems like its on BIOS) although if I hit another key first before hitting F10 and ENTER, it won't restart and just stays on.
4. if I remove the LCD connector from the board, the laptop will never stays on if I turn it on, it will automatically shutdown after 20 seconds (like #1) even if I do a click. In short, I can't do #2 if the LCD connector is disconnected from the board.
5. I triend connecting an external monitor in all the different set-up above using usb-c to hdmi connector and I don't get any display. But I don't even know if this type of laptop works like other common brand like Dell, Asus, HP, Samsung where you can simply tell that there's an issue on the gpu if there's still no display even on external monitor.
6. I've tried all the steps above both battery plugged and un-plugged and the results are the same
This is the weirdiest issue I ever encounter specially the #2 and #4. like how does the click event and lcd screen connector affect the boot/power process of the laptop?
at first I thought it was the screen, then since I connected it to external monitor and no display, I had wonder if it was the GPU. although I was a bit conern of its primary behavior of auto shutdown after turning on, but after some testing out curiousity, things even got more weird, and I have more doubt if it was a gpu issue since its auto shutting down or not auto shutting when it detects a click. and whats more, theres that LCD connector that also affect its boot behavior when unplugged.
I don't want to ask my friend to buy a $300-$400 new lcd just for testing if I get a display or not.
Also, take note that this board design is similar to macbook, it has 8V on main power, then there's 5V and 3.2V and the screen has 29V.
CPU - Intel Core i7-8550u
GPU - Nvidia Geforce MX150
Ram- 16GB(4x4) soldered on-board
I/O - 2 USB-C (1 supports thunderbolt), 1 USB-A
Here on this link https://bradshacks.com/matebook-x-pro-te... (under electronics tab) you will see its internal component.
I appreciate if someone can advise on what might be the problem, and what else I can do for additional diagnosis.
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