My phone is Vivo Y66L, Android version 6.0.1, Processor 1.4GHz Snapdragon MSM8937, Vivo ROM Funtouch OS_3.0, never succeeded in rooting it.

I can only access Storage\emulated\0, when I connect my phone to my computer this is also what's visible in the computer, I had installed many applications and their data are invisible to me except what little I can find at Storage\emulated\0\Android\data and Storage\emulated\0\Android\obb, most of them are games and I don't intend to lose any progress.

I had successfully clean reinstalled OS to my computer countless times, using USB stick+WinPE+WinNTSetup, recently I learned the commands to install Windows with dism and bcdboot...

But Android is very different, first of all I can't connect a USB stick to my phone, also Android won't allow me to boot into the USB stick, and the SSD is built-in, and the firmware...

However I do know a trick or two, though I cannot say that I am an expert on this; I have installed Android Studio on my computer, where can I find custom ROM compatible to my device? Can I use any ROM? How can I make backups? How can I flash my phone with ADB? I say thanks in advance.

  • 3
    Android Studio is for developing apps only. For custom ROMs you need to search the internet. Make sure the custom ROM has been developed exactly for your device model. Otherwise it will with 99.9% not work or even brick your device. How to install a custom ROM depends on the device. Commonly such things can be found in xda-developers forum - if they exist.
    – Robert
    Dec 30 '20 at 17:19
  • you can't flash with adb at all, and there is no custom ROM. you can root your device with Magisk and backup your apps with Migrate, but you need a flash tool for this. or try one-click-routing apps like KingRoot, but in case you brick all data is lost
    – alecxs
    Dec 30 '20 at 19:40
  • for qualcomm devices check out EDL mode, that should allow to flash magisk_patched.img on locked bootloader (experts only) android.stackexchange.com/q/224131 android.stackexchange.com/q/226838
    – alecxs
    Dec 30 '20 at 19:51