[Android Q&A, Help & Troubleshooting] chris-hac:
I have the same type of tablet/issue

The Fujitsu Stylistic M702 has great specs:

i like the Hamann/Kardon Sound and that it is waterproof as well as the big accumulator.

The crux with this tablet is that Fujitsu obviously dropped any development for it. My email to the support was quoted wit a hint to the latest update of 2013 - Android 4.0.4

The Tablet itself seams to have no accessible recovery on it,(none of the common button combinations seamed to work) the Update is done trough a vendor specific app. The system image is packed in a .enc file wich seams to be encryptd binary.

The filesystem is accessable trough ADB but the android is realy well secured, someone did his homewok well here

shell@android:/system $ ls -la
drwxr-xr-x root root 2013-05-24 05:52 app
drwxr-xr-x root shell 2013-05-24 05:50 bin
-rw-r--r-- root root 3975 2013-05-24 05:45 build.prop
drwxr-xr-x root root 2013-05-24 05:53 etc
drwxr-xr-x root root 2013-05-24 05:46 fonts
drwxr-xr-x root root 2013-05-24 05:51 framework
drwxr-xr-x root root 2013-05-24 05:50 lib
drwxr-xr-x root root 2013-05-24 05:46 media
drwxr-xr-x root root 2013-05-24 05:45 tts
drwxr-xr-x root root 2013-05-24 05:46 usr
drwxr-xr-x root shell 2013-05-24 05:46 vendor
drwxr-xr-x root shell 2013-05-24 05:50 xbin
shell@android:/system $ cd ..
shell@android:/ $ ls -la
drwxr-xr-x root root 2015-10-16 17:09 acct
drwxrwx--- system cache 2015-10-16 18:11 cache
-rw-r--r-- root root 11764 1970-01-01 00:00 chargemode.rc
drwxr-xr-x system system 1970-01-01 00:00 cnt
dr-x------ root root 2015-10-16 17:09 config
lrwxrwxrwx root root 2015-10-16 17:09 d -> /sys/kernel/debug
drwxrwx--x system system 2015-10-16 18:02 data
-rw-r--r-- root root 851 1970-01-01 00:00 default.prop
drwxr-xr-x root root 2015-10-16 17:10 dev
lrwxrwxrwx root root 2015-10-16 17:09 etc -> /system/etc
drwxrwx--x system system 2012-04-05 12:26 fota2
-rwxr-x--- root root 107088 1970-01-01 00:00 init
-rwxr-x--- root root 5684 1970-01-01 00:00 init.fj_dev_board.usb.rc
-rwxr-x--- root root 2344 1970-01-01 00:00 init.goldfish.rc
-rwxr-x--- root root 29216 1970-01-01 00:00 init.rc
-rwxr-x--- root root 17228 1970-01-01 00:00 init.tegra3.rc
-rwxr-x--- root root 13328 1970-01-01 00:00 kernel.tegra3.rc
-rwxr-x--- root root 23393 1970-01-01 00:00 kernelmode.rc
drwxrwx--x system system 1970-01-01 00:00 kitting
-rwxr-x--- root root 27056 1970-01-01 00:00 maker_cmd.rc
drwxrwxr-x root system 2015-10-16 17:09 mnt
drwxr-xr-x system system 2012-01-16 02:15 persdata
drwxrwx--x system radio 2012-01-01 00:00 persist
drwxrwx--x system radio 2000-04-16 05:09 persist2
dr-xr-xr-x root root 1970-01-01 00:00 proc
drwx------ root root 2013-05-24 05:46 root
drwxr-x--- root root 1970-01-01 00:00 sbin
lrwxrwxrwx root root 2015-10-16 17:09 sdcard -> /mnt/sdcard
drwxrwx--- root root 2000-04-16 05:09 sst
drwxr-xr-x root root 2015-10-16 17:09 sys
drwxr-xr-x root root 1970-01-01 00:00 system
-rw-r--r-- root root 272 1970-01-01 00:00 ueventd.goldfish.rc
-rw-r--r-- root root 4494 1970-01-01 00:00 ueventd.rc
-rw-r--r-- root root 2043 1970-01-01 00:00 ueventd.tegra3.rc
lrwxrwxrwx root root 2015-10-16 17:09 vendor -> /system/vendor

The manual root methods as well al the rooting apps i tryed all failed.

i now made a full backup of the device via adb and will see if i can get some info about the system by taking the backup file appart.

It would b great to get some hints from a developer how to gain administrative access to this device.

Thank you very much to all willing to help :)