[Xperia Z5 Compact Q&A, Help & Troubleshooting] solarlogos:
Hello Ladys and gentleman, i´m new to this community and this is my first post, i got advised on a stackexchange to post my question here and i hope this is the right place - I searched the internet for days but i didnt find my exact/similiar problem.

In before, i have a technically background and familiar with scripting and bash and such but all this android stuff is rather a black box for me, So i have a Sony Xperia Z5 C and about two years ago i struggled many hours to unlock/root the phone and install a custom ROM, only thing i can say is that it wasnt sth popular like cyanogenmod at that time, i got the ROM in some x5C developer forum maybe even this one but after two years i dont know a thing what i actually did. The ROM came with superSu - next i installed droidwall. A firewall whitelist only for browser was the main reason to use a custom rom, next to remove all bloatware. so everything went fine for these two years. Then all of a sudden the droidwall stopped working and google playstore updated several apps and my setup was compromised.

Super Su also asked to update, i thought i maybe need the update because superSu doesnt work anymore -> the firewall cant sudo anymore -> the reason it doesnt work.

So i tried the superSu update: there was a modal which said "install normaly" or "install CRWM/TWRP" <- sth. like this. because there said crw/twrp is recommended for htc-one i "accidently" clicked "install normaly" after installing there was a restart and since then the phone doesnt boot anymore. After showing the sony loading icon the LED blinks 3 times red and a fourth time but longer and the phone restarts this process over and over again, i´m only able to stop it by pressing power button + vol-up "3 times vibrate" then it seems to be off. People on the Internet say that its a code for broken hardware but it was definetly the superSu update.

I looked into this again and found i could pull files with adb, so I just loaded the latest android sdk and copied adb and fastboot to a folder like recommended in many posts but adb devices doesnt show anything but fastboot devices does recognize my phone.

fastboot lists my phone like:

CB5Axxxx96F fastboot

to fix phone not listed by adb i tried

echo 0x0dde >> adb_usb.ini

adb kill-server

adb devices

but no luck, i also installed pc-companion but no luck i tried all those with holding vol-down + plug cable in "green led" and holding vol-up + plug cable in "blue led" and also with administrative rights but no luck also. The battery is loaded 100%, but the loading icon only shows up after "120 seconds pressing off button near SIM" also tried without simcard. I´m pretty sure i had developer options activated and usb debugging but most probably it was in mtp mode and i cant check or change it now.

im on mac osx (Sierra 10.12.3) by the way and got the product-id from usb-information So the worst thing that could happen would be loosing all my data on the phone. So right now i have no idea what to do and i´m scared of doing sth accidently again,

Can somebody explain what actually could have been happend and what my options are to either "recover the phone" so its just working as it did before or at least get all the images and data / filesystem-access and install a new OS ?!