Phone suddenly shut down and won't boot up

Question

My phone (Xiaomi Redmi Note 10, 2 years usage, the warranty just passed) suddenly shut down at 50% battery at normal usage when I clicked an app to open it and it will not boot up. I want to fix it myself due to privacy reasons, as I don't trust payed services and have experience in opening phones, but only to replace the screens.

I tried to turn it on on safe mode - unsuccesfully. I tried to charge it but it didn't even pop the animation of charging. Nontheless I left it for couple hours to charge and tried again - still not booting up. The USB connector is clean, dust-free and not loose. I tried different chargers. It is not detected by the computer when plugged in (checked in the Device Manager, Windows). I also called the phone from another phone to check if it's the screen's issue - I got "user out of service" message.

I tried to troubleshoot the connector and it was a surprise to me: I own a MakerHawk UM34C USB 3.0 tester and tried it on my working phone - readings were reasonable, approx. 13W of charging power. I tried it on bunch of other devices, with correct readings. I also tested a device with physical on/off switch and the device showed voltage of 5V when turned off (charger voltage) and voltage + amperage when turned on (with propper readings). So when I plugged it in the phone and if the connector were bad then I should have the same reading as in the device with off switch. But what I got was device (tester) restarting constantly without even showing me the data, as if the connection was ok but the phone "intentionally" disconnected it repeatedly. This means that the phone recognises the charger and disconnects it immediately. What does it imply? Is it the software issue?

I tried to open it like on the vid, using same tools but the glue seems to be too strong and it won't open so I can't check the battery itself without damaging the phone: https://www.youtube.com/watch?v=PhC37fp4o7Y

How should I troubleshoot the issue?

These threads provided no help:

Galaxy S4 Not booting up

POCO M3 Pro 5g not booting up after unexpected shutdown. It does not charge as well

In advance, thanks for help.

Answer 1

Even i faced the same issue with my Redmi note 10 pro. My phone abruptly used to turn off randomly anytime even when the phone has more than 50% of charge. Most of the time it used to get turned on after long pressing the power button but once it didn't turned on. I tried everything but didn't work.

How I solved the issue: I open the phone disconnected all the cables and connected it back. After connecting it to charger, it turned ON!

You can try, if you have all the proper tools. I just needed a hair dryer, some cards and a screwdriver.

Hope this finds you helpful.