[Samsung Galaxy S10 Questions & Answers] masterbricklayer:
Hello,

I purchased a G970F for the second time because I hard-bricked the first one due to not exercising as much caution, and since then, I've learned about the added difficulty the S10 generation has compared to the only other Samsungs I've had the displeasure of working with (S5, S4). I've read a number of guides since then, but I'm not entirely sure which still apply and which do not, since a lot of them are from 2019 / early 2020, and I've somehow managed to only soft-brick it once before bringing it back to current condition.

So, where I stand with my G970F:

Bootloader unlocked, downloaded the latest firmware via Frija (Android 11), patched the AP file, flashed the patched AP, along with BL, CP, CSC via Odin, booted with Magisk, then installed TWRP with SU privileges by downloading TWRP on the Play Store, going through the steps, yadda yadda. I've followed the two official guides (Official installation steps for Magisk by John Wu, and TWRP installation guide for Samsung Galaxy S10e (Exynos), also on the official page.

This is where I get stuck. I've come across some older guides on XDA that mention flashing multi-disabler, as well as mention of disabling FBE immediately after installing TWRP, on the TWRP 3.4.0 for Galaxy s10 Exynos thread on XDA. I don't know if these still apply (they're from 2019), because when I tried disabling FBE and booting to TWRP, it still shows the directories as encrypted hash, and when I tried flashing the multi-disabler on TWRP and rebooting, it gets stuck on Samsung splash (soft bricked), so I had to reboot to TWRP, reboot to download mode via ADB, then reflash the firmware with patched OS to start over. Multi-disabler soft-bricked my device, so I'm guessing it's not compatible with devices with Android 11?

The end goal for me here is to flash a custom rom safely, but I'm concerned about a few things:

The first time I hard-bricked my first G970F, it was during a root attempt, and the last thing I did was wipe data on TWRP, flash a zip, and reboot - and this essentially made it impossible to get into either Download mode or Recovery, it would just vibrate on black screen, stuck in a forever boot loop with no means to turn it off. I had to open the device to manually disconnect the battery.

I'm being extra cautious not to repeat the above scenario, so here is where my concern is: I've read that S10 series only have an A partition which leads to Magisk having to reside in a parasite-like existence with recovery, and the other landmine is that there is a 'VaultKeeper' that locks up the bootloader if an unauthorized OS is detected or some sort? I'm thinking that maybe either of these was responsible for my first G970F being stuck in an unbootable state, so I want to navigate carefully here.

I want to flash one of the unofficial roms linked on XDA by @expressluke , and I have Magisk patched AP + stock firmware + TWRP, only steps I have taken were from the two official guides (not XDA threads) for TWRP and Magisk, which never mentioned 'multi-disabler' nor disabling FBE. From my current state, how do I go about flashing the custom rom without potentially damaging recovery / partitions / triggering some Samsung trap like VaultKeeper? I'm a bit keen to do this, since it looks like having Magisk + stock firmware for some reason only recognizes my storage as 32GB instead of 128GB.