Could custom recovery be flashed after rooting the phone and how to make a NANDroid backup

[daopeng]

I have a Hisense A7 with bootloader unlocked and magisk installed and now I have successfully rooted it following the instructions. Kudos to the author TomKing062 for this brilliant project. My question is, now that I have the phone rooted, will flashing a custom recovery such as TWRP break it, if yes, is there a way to make a full stock ROM backup so that if anything goes wrong I could flash it back? Is it possible to use spreadtrum to do the trick? Thanks a million.

[daopeng]

So I used adb shell su -c 'dd if=/dev/block/by-name/[<boot>|<vbmeta_system>|<super>|...]' > [<boot>|<vbmeta_system>|<super>|...].img to get a bunch of imgs backed up to my PC, I guess this more or less provides some comfort for me, though I doubt if something goes wrong, I will be able to flash them back and get to where I am now.
Another thing is I learned that I might as well have used fastboot boot twrp.img to temporarily boot into twrp and perform a NANDroid backup there. But I didn't do that to test it out.

[TomKing062]

1. backup with dd would be faster than spd_dump/ResearchDownload
2. recovery can't be modified (unless use 38691)
3. fastboot boot not work

although a7(ud710) can use 38691 to sign custom boot chain, it still need a (full work) TWRP device tree

[daopeng]

Thanks so much for your reply. Alright then, looks like I'm gonna hang on to what I have now then, which is perfect.