[Sprint HTC One (M8)] mojomojo_man:
Ok. Wiped. Reflashed. Similar story. Except I realized it was only the Chrome update that caused the FC and it happens as soon as it starts downloading. I'm able to selectively pick and choose some updates and was able to get TB and aLogcat installed but Camera was same ("Insert an SD card before using the camera"). aLogCat wouldn't save the logs so I used ADB to get a shell and this is where it got interesting. (I know my way around Debian and a few Linux distros but Android still confuses me.)

E:\ANDROID>adb shell
shell@htc_m8:/ $ su
root@htc_m8:/ # ls -al
drwxr-xr-x root root 2016-01-29 21:41 acct
drwxrwx--- system cache 2016-01-29 20:35 cache
drwxrwx--x system carrier 2015-12-26 21:08 carrier
lrwxrwxrwx root root 2016-01-06 09:19 charger -> /sbin/healthd
dr-x------ root root 2016-01-29 21:41 config
drwxr-xr-x root root 1969-12-31 18:00 custdata
-rw-r--r-- root root 1393 2016-01-06 09:19 cwkeys
lrwxrwxrwx root root 2016-01-29 21:41 d -> /sys/kernel/debug
drwxrwx--x system system 2016-01-29 22:22 data
-rw-r--r-- root root 678 2016-01-06 09:19 default.prop
drwxr-xr-x root root 2016-01-29 21:41 dev
drwx------ root root 2016-01-24 21:46 devlog
lrwxrwxrwx root root 2016-01-29 21:41 etc -> /system/etc
drwx------ root root 2016-01-23 15:31 fataldevlog
-rw-r--r-- root root 60698 1969-12-31 18:00 file_contexts
drwxrwx--x system system 2016-01-29 21:41 firmware
-rw-r----- root root 2224 1969-12-31 18:00 fstab.qcom
-rwxr-x--- root root 580548 2016-01-06 09:19 init
-rwxr-x--- root root 1031 1969-12-31 18:00 init.environ.rc
-rwxr-x--- root root 93 2016-01-06 09:19 init.htc.audio.sh
-rwxr-x--- root root 1797 2016-01-06 09:19 init.network.sh
-rwxr-x--- root root 5937 2016-01-06 09:19 init.power.rc
-rwxr-x--- root root 10121 2015-11-30 10:23 init.project.rc
-rwxr-x--- root root 5254 2016-01-06 09:19 init.qcom.audio.sh
-rwxr-x--- root root 7439 2016-01-06 09:19 init.qcom.class_core.sh
-rwxr-x--- root root 6073 2016-01-06 09:19 init.qcom.early_boot.sh
-rwxr-x--- root root 12037 2016-01-06 09:19 init.qcom.factory.sh
-rwxr-x--- root root 2910 2016-01-06 09:19 init.qcom.firmware_links.sh
-rwxr-x--- root root 29108 2016-01-06 09:19 init.qcom.post_boot.sh
-rwxr-x--- root root 2736 2016-01-06 09:19 init.qcom.ril.sh
-rwxr-x--- root root 6984 2016-01-06 09:19 init.qcom.sh
-rwxr-x--- root root 4561 2016-01-06 09:19 init.qcom.ssr.sh
-rwxr-x--- root root 2804 2016-01-06 09:19 init.qcom.syspart_fixup.sh
-rwxr-x--- root root 18771 2016-01-06 09:19 init.qcom.wifi.sh
-rwxr-x--- root root 39745 1969-12-31 18:00 init.rc
-rwxr-x--- root root 2890 2016-01-06 09:19 init.ril.rc
-rwxr-x--- root root 31160 2016-01-06 09:19 init.target.rc
-rwxr-x--- root root 2446 2016-01-06 09:19 init.trace.rc
-rwxr-x--- root root 26892 2016-01-06 09:19 init.usb.rc
-rwxr-x--- root root 2106 2016-01-06 09:19 init.usbdiag.sh
-rwxr-x--- root root 301 2016-01-06 09:19 init.zygote32.rc
drwxr-xr-x root system 2016-01-29 21:41 mnt
drwxr-xr-x root root 2016-01-06 09:19 oem
drwxrwx--x system system 2016-01-29 21:41 persist
dr-xr-xr-x root root 1969-12-31 18:00 proc
-rw-r--r-- root root 6747 2016-01-06 09:19 property_contexts
drwx------ root root 2016-01-29 21:41 ramdump
drwxr-xr-x root root 2016-01-06 09:19 res
drwx------ root root 2015-12-24 12:05 root
drwxr-x--- root root 2016-01-06 09:19 sbin
lrwxrwxrwx root root 2016-01-29 21:41 sdcard -> /storage/self/primary
lrwxrwxrwx root root 2016-01-29 21:41 sdcard2 -> /storage/ext_sd
-rw-r--r-- root root 2217 2016-01-06 09:19 seapp_contexts
-rw-r--r-- root root 67 2016-01-06 09:19 selinux_version
-rw-r--r-- root root 242521 1969-12-31 18:00 sepolicy
-rw-r--r-- root root 14079 2016-01-06 09:19 service_contexts
drwxr-xr-x root root 2016-01-29 21:41 storage
drwxr-xr-x root root 2016-01-29 20:27 su
dr-xr-xr-x root root 2016-01-29 21:41 sys
drwxr-xr-x root root 1969-12-31 18:00 system
lrwxrwxrwx root root 2016-01-29 21:41 tombstones -> /data/tombstones
-rw-r--r-- root root 8210 2016-01-06 09:19 ueventd.qcom.rc
-rw-r--r-- root root 6687 2016-01-06 09:19 ueventd.rc
-rw-r--r-- root root 216 2016-01-06 09:19 ueventd.target.rc
drwxrwx--x system system 2016-01-29 21:41 vendor
root@htc_m8:/ # cd /sd
sdcard/ sdcard2/
root@htc_m8:/ # cd /sdcard
root@htc_m8:/sdcard # ls -al
opendir failed, Permission denied
s -al /storage/self/primary
lrwxrwxrwx root root 2016-01-29 21:41 primary -> /mnt/user/0/primary
root@htc_m8:/sdcard # ls -al /mnt/user/0/primary
lrwxrwxrwx root root 2016-01-29 21:41 primary -> /storage/emulated/0
root@htc_m8:/sdcard # ls -al /storage/emulated/0
opendir failed, Permission denied
1|root@htc_m8:/sdcard # ls -al /storage/emulated
opendir failed, Permission denied
1|root@htc_m8:/sdcard # ls -al /storage
drwxrwx--x root sdcard_rw 1969-12-31 18:00 3338-3063
drwx--x--x root sdcard_rw 2016-01-29 02:51 emulated
lrwxrwxrwx root root 2016-01-29 21:41 ext_sd -> /storage/3338-3063
drwxr-xr-x root root 2016-01-29 21:41 self
root@htc_m8:/sdcard #
root@htc_m8:/sdcard # mount
rootfs / rootfs ro,seclabel,relatime 0 0
tmpfs /dev tmpfs rw,seclabel,nosuid,relatime,mode=755 0 0
devpts /dev/pts devpts rw,seclabel,relatime,mode=600 0 0
none /dev/memcg cgroup rw,relatime,memory 0 0
none /dev/cpuctl cgroup rw,relatime,cpu 0 0
proc /proc proc rw,relatime 0 0
sysfs /sys sysfs rw,seclabel,relatime 0 0
selinuxfs /sys/fs/selinux selinuxfs rw,relatime 0 0
debugfs /sys/kernel/debug debugfs rw,seclabel,relatime 0 0
none /sys/fs/cgroup tmpfs rw,seclabel,relatime,mode=750,gid=1000 0 0
none /sys/fs/cgroup/memory cgroup rw,relatime,memory 0 0
none /acct cgroup rw,relatime,cpuacct 0 0
tmpfs /mnt tmpfs rw,seclabel,relatime,mode=755,gid=1000 0 0
/dev/fuse /mnt/runtime/default/emulated fuse rw,nosuid,nodev,noexec,noatime,user_id=1023,group_id=1023,default_pe
rmissions,allow_other 0 0
/dev/fuse /mnt/runtime/read/emulated fuse rw,nosuid,nodev,noexec,noatime,user_id=1023,group_id=1023,default_permi
ssions,allow_other 0 0
/dev/fuse /mnt/runtime/write/emulated fuse rw,nosuid,nodev,noexec,noatime,user_id=1023,group_id=1023,default_perm
issions,allow_other 0 0
/dev/block/vold/public:179,33 /mnt/media_rw/3338-3063 texfat rw,dirsync,nosuid,nodev,noexec,relatime,uid=1023,gid
=1023,umask=0007,allow_utime=0020,codepage=437,iocharset=utf8,min_prealloc_size=64k,max_prealloc_size=60874k,read
ahead=4M,fail_safe,discard,hidden=show,errors=continue 0 0
/dev/fuse /mnt/runtime/default/3338-3063 fuse rw,nosuid,nodev,noexec,noatime,user_id=1023,group_id=1023,default_p
ermissions,allow_other 0 0
/dev/fuse /mnt/runtime/read/3338-3063 fuse rw,nosuid,nodev,noexec,noatime,user_id=1023,group_id=1023,default_perm
issions,allow_other 0 0
/dev/fuse /mnt/runtime/write/3338-3063 fuse rw,nosuid,nodev,noexec,noatime,user_id=1023,group_id=1023,default_per
missions,allow_other 0 0
/dev/block/platform/msm_sdcc.1/by-name/system /system ext4 ro,seclabel,noatime,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/userdata /data ext4 rw,seclabel,nosuid,nodev,relatime,discard,noauto_da_al
loc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/cache /cache ext4 rw,seclabel,nosuid,nodev,relatime,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/devlog /devlog ext4 rw,seclabel,nosuid,nodev,relatime,errors=continue,data
=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/fataldevlog /fataldevlog ext4 rw,seclabel,nosuid,nodev,relatime,errors=con
tinue,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/custdata /custdata ext4 ro,seclabel,nosuid,nodev,relatime,data=ordered 0 0

/dev/block/mmcblk0p37 /carrier ext4 rw,seclabel,nosuid,nodev,noatime,grpid,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/radio /firmware/radio vfat ro,relatime,uid=1000,gid=1000,fmask=0337,dmask=
0227,codepage=cp437,iocharset=iso8859-1,shortname=lower,errors=remount-ro 0 0
/dev/block/platform/msm_sdcc.1/by-name/adsp /firmware/adsp vfat ro,relatime,uid=1000,gid=1000,fmask=0337,dmask=02
27,codepage=cp437,iocharset=iso8859-1,shortname=lower,errors=remount-ro 0 0
/dev/block/platform/msm_sdcc.1/by-name/wcnss /firmware/wcnss vfat ro,relatime,uid=1000,gid=1000,fmask=0337,dmask=
0227,codepage=cp437,iocharset=iso8859-1,shortname=lower,errors=remount-ro 0 0
tmpfs /storage tmpfs rw,seclabel,relatime,mode=755,gid=1000 0 0
/dev/fuse /storage/emulated fuse rw,nosuid,nodev,noexec,noatime,user_id=1023,group_id=1023,default_permissions,al
low_other 0 0
/dev/fuse /storage/3338-3063 fuse rw,nosuid,nodev,noexec,noatime,user_id=1023,group_id=1023,default_permissions,a
llow_other 0 0
/dev/block/loop0 /su ext4 rw,seclabel,noatime,data=ordered 0 0
root@htc_m8:/sdcard #

that didn't paste so great and its too many premature line ends to fix manually but I think this bit here sums up the problem:

root@htc_m8:/ # ls -al sdcard
lrwxrwxrwx root root 2016-01-29 21:41 sdcard -> /storage/self/primary
root@htc_m8:/ # ls -al /storage/self/primary
lrwxrwxrwx root root 2016-01-29 21:41 primary -> /mnt/user/0/primary
root@htc_m8:/ # ls -al /mnt/user/0/primary
lrwxrwxrwx root root 2016-01-29 21:41 primary -> /storage/emulated/0
root@htc_m8:/ # ls -al /storage/emulated/0
opendir failed, Permission denied
1|root@htc_m8:/ # ls -al /storage/emulated
opendir failed, Permission denied
1|root@htc_m8:/ # ls -al /storage
drwxrwx--x root sdcard_rw 1969-12-31 18:00 3338-3063
drwx--x--x root sdcard_rw 2016-01-29 02:51 emulated
lrwxrwxrwx root root 2016-01-29 21:41 ext_sd -> /storage/3338-3063
drwxr-xr-x root root 2016-01-29 21:41 self
root@htc_m8:/ #

OMG... what is their love affair with symlinks??? that makes my head spin... I can only assume root should have access to /sdcard (aka /storage/self/primary aka /mnt/user/0/primary aka /storage/emulated/0)

I ran a dmesg but it didn't look useful. Just a lot of battery/PM nonsense. Not sure where the logs are stored in Android. Not /var/log so I'm lost.

I have to go walk the dog before he takes matters into his own "hands" on my carpet. When I get back i'll flash something else to make sure it's not a hardware issue with my internal flash or something. If you want me to run something else and post the output lemme know soon. I really need this phone working well by tomorrow afternoon as I need the navigator but I can run a few more tests before I flash.

i really hope I'm not wasting your time and its not my hardware admittedly mostly cause i'd really hate that my phone was broke before i paid it off... yes i'm a self-centered ass.

If your sick of listening to me ramble on then just ignore me and I'll buzz off. I know I'm an ass I just can't help it really and stopped trying to a long time ago.

EDIT: Ugh.. ok something very wrong with my /sdcard partition. TWRP won't format it. It's my problem. Maybe some mod can delete all this crap I dirtied up your thread with. I may have to RUU to get this fixed if TWRP won't do it. Sorry.

EDIT2: Yaayy! I'm an idiot!!! lol. latest version of TWRP fixed my /sdcard partition. was using 2.8.6.1 now 2.8.7.0!! Weird that it worked so many times before and then failed me right then when it I needed it most. I probably glazed right over the error message the last time I flashed internal storage. Anyway... I think its going to work now. So uhh... how's everyone else doing today?