[Galaxy S 5 Q&A, Help & Troubleshooting] BruceElliott:
Thank you, Ibuprophen; I will post the question as you suggest, out of curiosity. I tried it anyway last night and it did not restore boot. After recovering my data and taking a full nandroid backup using TWRP, I finally flashed the latest version of the S5 stock ROM (dated March 2017, which is what I had on my bricked phone) downloaded from Sammobile. That indeed restored boot and and left me at the new phone startup procedure and back at the dreaded beginning of a system configuration oddessy that has evolved over years.

In an attempt to shortcut that, I flashed only the /data partition from the nandroid backup. But of course the /data partition backup included all apps and their settings, including BK Disabler and its XML file of disabled apps including the disabled system apps preventing boot. So now my phone is back at an unbootable state; but at least I know that the problem is in the /data partition. Using the terminal app in TWRP, I found BK Disabler in /data and its dependent files in /data/data. I have not yet found BK Disabler's XML file listing all of the disabled apps. Once I do, I will delete those entries, rename BK Disabler apk and files, and create a nandroid of the resulting "old" /data partition minus BK Disabler. Then I will flash the entire stock ROM again from Odin, but without reboot. As I understand it, at first boot the system creates the master "oat" file from apps in the /data partition and then modifies that file as new apps are properly installed. If so, it makes sense that one could not abruptly flash a different /data without the rest of the system knowing what's going on.

So, after flashing again to stock without reboot, I will flash the backup /data with all of my "old life" but hopefully minus the offending BK Disabler apk and dependent files. Then, when I boot to this jury-rigged system for the first time, hopefully the new phone startup process will be happy with the modified /data partition and go merrily on its way by creating the system oat file to include all of my old apps, etc. I even found the system settings file in /data/data, so if this works, even those should be retained.

Another, more laborious process, would be to try to find all of the system executables whose "execute" permission has been set to "no execute" by BK Disabler and use the chmod command in TWRP to restore those permissions. Too much fun...

But please, if anyone has read this far and has any input on these procedures I would love to know. One problem that I am encountering is that the linux bash command environment seems to be quite limited in TWRP, which makes sense as this a recovery environment after all. But if anyone knows how to flash some extension of the bash environment to/with TWRP, that might be helpful. It could, for example, allow me to quickly search for all system files with the "no execute" permission set.

All of this is getting a bit burdensome for a person whose hobby is not phone hacking, so my mind wanders to a dresser drawer full of old flip phones, some of which could probably be activated...:eek: Hey, that would be one way to beat the Google Monster, one of those flip phones and an old Garmin.:D

Cheers,

Bruce

P.S. Be careful with the NSAIDs.:)