Mi 9T suddenly died/won't turn on

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New member
Jul 20, 2016
yesterday my ~2 year old 9T just went into black screen while I was using it. It wasn't laggy/hot/wet at that moment or anything, it just straight went into black screen. The battery was on ~70%.
Holding down the power button, power button + volume up/down for a minute doesn't do anything.
Charging the phone on a confirmed charger over night, still nothing after trying the buttons again.
The only sign of life im getting is when I connect it to my computer.
Im getting a QUSB_BULK_CID:0404_SN:B54B8A07 entry in the device manager under other devices.
The phone was clean, no custom ROM, no TWRP or other bootloader, not rooted.

I saw some similar cases in this forum, but they usually involved at least some kind of TWRP or custom ROMs.
Also weird is al that I found researching this topic were some Qualcomm [...] entries in the device manager under connections (COM & LPT) while I have a different entry.

Now the questions are:
- Is there any hope for success with an software approach, meaning can I install some software which allows me to access the phone?
If yes how do I do it and will I lose all my data this way?

- Given that my computer at least recognizes my phone in some way, can I rule out some hardware issues or should I try to open it and at least check if there is something broken?

Note that I probably would have replaced this phone over the course of this year anyways, so visual damage doesn't bother me too much,
I'm much more interested in recovering my data or getting my phone to work so I can at least backup my stuff before moving to another phone.

If you need any more information I will try to provide it, I will be grateful for any help!


New member
Jan 26, 2022
Hi, you should get a battery replacement to discard a hardware issue. I replaced the battery on my 9T and I can confirm the phone won't boot or even power on without a battery despite the type of charger being used.