[ASUS ROG Phone II Questions & Answers] healerdan:
Hello there!

I have no experience with your problem. Just going to say that from the top. I've never torn a phone down, and when hardware components need replacing that's when I usually decide I need to pick up a new phone.

I just recommend you make sure the phone you're trying to fix like this actually needs it. I've messed with my tencent rog ii quite a bit lately and I have had the phone go completely black - thinking I had thoroughly destroyed my phone, but I was able to get it running again.

It's possible that the complete "power off" that you are reporting is the phone being in EDL mode as the phone gives no indication whatsoever that it is on when in EDL mode. As a hail mary maybe you should quickly try this before tearing your phone down.

go to this guide, and download the zip file in the main post.

https://xdaforums.com/t/repair-your-rog2-phone-with-edl-mode-official-firmware.4012175/

extract the zip, then go the the folder "qpst.win.2.7_installer_00453.2" and run "QPST.2.7.453.msi" - this installs the drivers necessary to communicate with your phone when in EDL mode (this may not be necessary, as your pc may identify a usb connection without this, but just to check 100% I'd install the drivers anyway.)

charge your phone for at least 30 minutes. just to make sure it's got juice.

use a DIFFERENT USB-C <-> USB-A cable than came with your phone (pick one up at the shop if you're not sure. ALSO plug your [charged] phone into your PC using the side USB port on the phone (Not the bottom usb port). This is because ASUS's cables don't seem to support flashing, so I'm suspicious if they'd work appropriately in this case, and because the side port is the only one that works for flashing and the like.

now open device manager (press windows key, type "device manager"). with that screen open, plug your phone in. On device manager you're hoping that a device appears under the menu "Ports (COM & LPT)" probably named something to do with Qualcomm.

if nothing shows up, unplug the usb port from the side and hold all three side buttons down for 20 seconds (vol +, vol -, and pwr) and keep an eye on the upper left side of the device where you MAY see a red light flash indicating signs of life. then plug it in again. if nothing happens unplug the phone, and hold the power button for 5 seconds, and plug it in again. if nothing happens, unplug it and try holding down just power and volume up for 20 seconds, then plug in again. If nothing happens, try power and volume down for 20 seconds, then plug in again. (you see where I'm going?) just make absolutely sure your phone has a hardware problem and can't connect to your PC in any way before performing surgery. If the device does show up under this "Ports (COM & LPT)" device it means your phone OS is thoroughly trashed. check out that same guide I linked, as well as this youtube for some ideas how to get it going again.

If your phone doesn't connect no matter what, and you're certain you've gotta get into the hardware, then I wish you the best of luck. I really wish I could be of any further assistance with regards to hardware. maybe if you do take that road let us know how it goes.

good luck!