Help! Android phone stuck in fastboot mode after using TWRP

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TL;DR

I have deleted everything off my phone using TWRP and now I can’t boot back into TWRP (it only automatically boots into fastboot mode). Have I done something wrong? If so, how could I fix it?

 

Details

So it’s my first time rooting an android phone and I have run into a problem. I recently bought a Xiaomi Mi 9T and went through the process to unlock and root it, because I wanted to install Lineage OS instead of using MIUI.

I started following the LTT tutorial on modding the Poco F1 to look like the Pixel 3 (https://www.youtube.com/watch?v=BsHtfLh6azw&t=194s – not the Mi 9T, but I think any Xiaomi phone would have pretty much the same process), and it was going fine until you have to download and flash TWRP to the phone. I did it and it worked, and so I booted into TWRP and went to wipe the phone. The LTT video says to only wipe the “Data” portion, but I had read that when wiping a phone there’s no reason not to wipe other stuff as well, so I think I chose to wipe Data, Cache, Dalvik cache, Internal storage and System (it was a brand new phone, so I just wiped everything that made sense to start clean).

Well after that I think I rebooted, but when it turned back on it booted straight into fastboot mode. I thought this was weird, but I just held the power button to turn it off (to boot into TWRP again to continue with the install of Lineage OS). Unfortunately, it booted straight back into fastboot mode, and ever since then I haven’t been able to boot into anything else (I can’t even shut it down, every time I hold the power button in it just automatically restarts into fastboot, so I just have to unplug it and wait for it to turn off itself).

So I then tried re-flashing TWRP to start the whole process again and to boot back into it, but now I get this error message (see attached image).

 

So my question is; have I done something bad by deleting all of the data and System OS at the same time? I’m worried that I’ve really messed something up by deleting all of the stuff I did, because I’ve read that it’s possible (however unlikely) to brick a phone by using TWRP incorrectly.

 

Any help would be greatly appreciated.

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25 minutes ago, huilun02 said:

Please avoid guides that are not written by the ROM dev himself or user feedback on the official XDA thread. And most certainly do not wipe or format partitions when there are no instructions to do so.

 

Hold down the appropriate buttons to boot into recovery, not system. Holding down just the power button boots into system, not recovery. You wiped your system partition, so it will obviously not boot to system correctly.

 

In the worst case scenario, just flash stock firmware using Miflash with the phone in fastboot mode. That will restore it to brand new condition and you can attempt to install custom recovery/ROM again.

 

For any assistance, please post on the appropriate XDA ROM thread. Not on LTT. Thank you.

 

 - Sent on the same damn phone but with Pixel Experience rom

Thanks for the advice, as I said I'm a newbie at this so it all really helps.

Just to clarify, I was indeed trying to boot into recovery mode (on the Mi 9T it is power + volume up buttons), but that still wasn't working.

I think I will just reinstall MIUI and start again, that seems like the longer but more secure way of doing it.