I have a Samsung Galaxy S5 G900H. It had the stock ROM, and is quite old and slow, so I was asked to put something newer on it, and I got LineageOS.
As my previous experiences with Samsung phones, the usual trouble occurred, with USB communications failing for no reason, getting drivers, messing with ADB, etc.
This time however I got to a stump - it simply won't mount the cache partition. I have installed the TRWP of this phone (k3gxx) with Odin, and even tried 3 different versions. The cache can never be mounted, not to format it nor to actually install the ROM, and since other things were formatted before the recovery got stuck on the cache, the phone is now bricked, as far as I could tell.
Googling only resulted in answers such as "can't mount cache? go into recovery mode, mount cache, and clear it", but I am not sure I can follow the logic of mounting the cache to fix the problem of not being able to mount the cache.
Fastboot of course cannot help, since this is a Samsung phone.
I can freely get into Download and Recovery modes.
Is there anything actually left to do?