[Redmi 10X / 10X Pro Questions & Answers] Leni_:
Hi. I got a Xiaomi Redmi 10C (fog/rain) and wanted to install another system because I dislike MIUI. I decided on LineageOS 19.1 since it's based on Android 12 like the default OS MIUI 13. It's not an official ROM, but it worked alright until I decided to try another ROM, PixelExperience. This one is an official ROM, but after I tried flashing their recovery ROM, I can no longer access recovery mode and I can't use fastboot mode either, it is not detected. The phone still boots into LineageOS, and it works, but now I can't flash anything else anymore.

Flashing LineageOS

I followed several tutorials and guides for flashing custom ROMs on the Redmi 10C. In particular, this one has a link to the unofficial LineageOS ROM in question: https://www.getdroidtips.com/lineage-os-19-1-redmi-10c/. I unlocked the bootloader, installed the USB drivers, and then used flashed TWRP Recovery using fastboot mode. I will call this fastboot mode the "normal" fastboot, since it's the one that comes with the device. It's a black screen with the word FASTBOOT written in orange in the center (see the photo below).

At this point, everything worked, normal fastboot was detected and I could boot into it with either `adb reboot bootloader` or `adb reboot fastboot`. I could also boot into the TWRP recovery mode with `adb reboot recovery`, so I continued on and flashed the LineageOS ROM. Now the phone would boot normally into LineageOS, no problem except a minor detail: TWRP recovery was replaced by LineageOS recovery (which is expected), and that came with LineageOS fastboot as well (see photos below). Both modes have an option to switch to the other.

The issue with this is that LineageOS fastboot was now detected by the USB drivers, but the normal fastboot was not anymore. Just to make it clear: at this point I could choose to boot into either LineageOS recovery (`adb reboot recovery`), LineageOS fastboot (`adb reboot fastboot`), or normal fastboot (`adb reboot bootloader`). When in LineageOS recovery, the adb tool would work. When in LineageOS fastboot, the fastboot tool would work. But when in normal fastboot, the fastboot tool would not see any device, as if the phone was not connected.

Flashing PixelExperience

The issue with the normal fastboot mode not being detected was not a problem until it became one, when I decided to flash a PixelExperience ROM (this time official) that you can find here: https://download.pixelexperience.org/fog/. I followed the instructions in their Install Guide (https://wiki.pixelexperience.org/devices/fog/install/) with the exception of the "flashing the vendor boot partition" part. I skipped it for two reasons. First, the guide says "Download this vendor_boot.img file", where "this" is a link to the guide instead of a file download link (so basically a broken link). Second, I didn't need to flash the vendor boot partition to install TWRP, so I thought it would be ok, and if anything went wrong I would still have fastboot mode to flash TWRP again, right?... Well, I flashed the PixelExperience recovery ROM (since they say that "other recoveries may not work"), and that obviously didn't work because now I can no longer boot into recovery mode. Whatever I do, it just boots into the OS instead. Only the command `adb reboot bootloader` (or holding volume down when booting) gives me the normal fastboot mode, but it is still not detected! As a result, I have no recovery mode and my fastboot mode is useless.

I still have a working LineageOS, but it's not even rooted, so anything I try fails. I had no idea I could end up in a situation like this where the device isn't bricked but is still mostly useless...

Is there any way I can get back to a working recovery or fastboot? I asked on the Telegram channels of both LineageOS and PixelExperience but no luck so far.