Black screen and can't restart the phone

[yabbara]

Please tell us some basic information before asking for help:
Model Name: Asus Zenfone 9
Firmware Version: Latest Android 12 version
Rooted or not: No
Frequency of Occurrence:
APP Name & APP Version (If your issue relates to the app):
In addition to information above, please also provide as much details as you can, e.g., using scenario, what troubleshooting you've already done, screenshot, etc.
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So today, while I was using the phone, the screen turned black and now is stuck on the black screen. The phone is still on because I still feel the vibrations if I swipe back, and the green LED lights up when I double tap the screen to access the face recognition. However, the screen remains black no matter what.

I need to find a way to force restart the phone using hardware keys. The only option I found online was to hold press the power button until it shows me an option to restart. I have set up the settings so that the "hold press" of the power button activates google assistant, which is what happens when I do it.

What other options do I have now???

Thanks

[amitgil]

Hard reset is done by pressing the volume up together with the power key for a few seconds.

[Mattias_ASUS]

If you press volume down and power for 8 seconds then the device will do a hard reset.

[QuickH]

Mine does the same thing, happened when connect to android auto wireless, happened 4 times already!

I'm getting fed up with this phone and it's issues! 

Started having bugs after update to Android 13!

[MaciekJ]

I have Asus Zenfone 9 with latest software (always up to date). Today for the 2nd time I've seen black screen, phone is not acting, I'm not able to turn it on, not able to do hard reset, etc. I was also connecting it to various chargers just to eliminate possibility that battery is empy (it shouldn't be as I always keep no less than 40% of battery).

I had such situation 2 months ago and gave phone back to service. They returned phone after couple of days and it was on with my actual setup (so they didn't do a system reinstallation). The guy who gave it back to me was not able to explain what has happened, but they sent me instructions how to maintain hard restart (what I was trying to make many times before giving it back to service). So to me it was kind of strange case already.

Any thoughts what the problem can be? I love this phone, but if this problem reoccurs I'll need to switch to something more resistant.

Appreciate your inputs.

Cheers