I have galaxy note 4 with stock rom (Samsung's official ROM) and about two weeks ago it started to crush and then reboot every few minuets. In addition, the phone was very slow.
I tried everithing I could do without root, even Factory data reset, but the phone countinued to act the same so I decided to root it and install a cutom ROM. I installed twrp, I rooted the phone, wiped the phone and intalled the ROM (unofficial LineageOS ROM). After the twrp installed the ROM, I started it for first time and the ROM didn't loaded, it just continue to show the ROM's loading screen until the battary over (about 8 hours). I tried to flash the ROM again and I suddently noticed that every action I made with twrp (formating and flashing the new ROM) printed me an error:
Failed to mount /modem (invalid argument).
The error also happend in cwm recovery. I need your help. I have no idea whats coruppted in my devices and why this error occurred.