E:failed to mount /cache (invalid argument) - how to format?

I have a Asus Zenfone 2 and a few days ago it ran out of battery and turned off. Then after I charged it up and restarted it, it wouldn't turn on. It gets to the logo and the loading circle and just gets stuck there forever. I can get into recovery, but can't do anything in recovery, because everything gives this error: > E:failed to mount /cache (invalid argument) Trying to wipe cache, factory reset the phone, mount /system, flash a ROM from SD card, ADB sideload, everything gives the error multiple times. Factory reset formats /data fine, but when it gets to /cache, gives the error and aborts. Same thing with fastboot. I tried to flash TWRP (I have stock recovery) and I tried to erase and format cache through fastboot, but both give this error: > FAILED (remote: 'Can not mount the necessary partition') > >fastboot: error: Command failed Is there anything I can do to format the phone or somehow rebuild the partitions without being able to flash anything via recovery or fastboot? I don't know if tools like AFT or xfstk can do anything for me. Edit: I don't think the EMMC chip is dead, because the recovery partition is still fine, I can still boot into recovery and when I did a factory reset, it formatted /data without any errors, only had an error when it started formatting /cache. When I was looking for a solution to this problem, I read somewhere that sometimes when the device gets interrupted, like when it shuts down suddenly, to prevent data loss android would change permissions on the /cache partition to read only or something like that. This would certainly explain what happened to my phone. Just need to think of a way to access ADB shell on it to try to change permissions. Shell doesn't work in ADB sideload mode, that's the only ADB thing the stock recovery has. Is that a similar thing in fastboot by any chance?