Here is what i used (Try to follow step by step):I used multiple versions of Odin (3.14, 3.13, 3.10, 3.09) and Heimdall. I'm also unable to get stock roms to work.
When flashing TWRP with Odin, I set the TWRP image tar as AP.
I think it all happened like this:
Bought the phone second hand. Installed LineageOS 15 succesfully. As with my other S5, I followed the official LineageOS steps, but was unable to get Heimdall to work. (Possibly because of pre-installed Samsung drivers on my PC. Heimdall does work when uninstalling the Samsung drivers.) So I switched to Odin and flashed it successfully.
Some time later, when LineageOS 16 was released, I installed LineageOS 16 cleanly/freshly using the official steps, but got the same Heimdall problem again. (I didn't knew at that time that the Samsung drivers were the problem.) So I used Odin again. But the LineageOS 16 setup didn't went smoothly, I got crash reboots in the LineageOS setup and possibly later also crashes in the TWRP menu at some places. (I don't know exactly anymore.)
Now, months later, I'm attempting to try it again. I was scared to update my regular S5 (klte) because of this problem with my S5 plus (kccat6), but it went fine for my klte. But the kccat6 still has the same problem or worse, I'm unable to get into the TWRP menu anymore.
Is the phone bricked? (Download mode and flashing still work.)
Or maybe there is a hardware failure somehow?
Enter download mode
Samsung Odin 3.12.3, Then AP twrp-3.3.1-0-kccat6.img.tar
Then boot to Recovery And in TWRP, make sure you Wipe Data Type: YES, Restart Recovery, And then using the USB cable plugged in your PC drag and drop the Official LineageOS .zip file and flash it. (Flash Opengapps aswell)
It should boot up