Got it working, it was the CID.
I followed the tutorial there to change the CID:
http://richard.burtons.org/2016/07/0...on-an-sd-card/
Tutorial
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What You need:
Samsung EVO Plus Micro SD card (mine was a 64GB, 32GB seems to be working too)
Rooted Android Device
Compiled evoplus_cid (see above website)
CID of the internal MicroSD (see post before)
Steps:
0) Get Your microSD out of the Pocketbook by gently pressing on the smaller part of the microSD and pushing the whole card in the direction of the smaller side. Get your CID of the Pocketbook microSD via ReadCID. Output should look like:
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\.\PhysicalDrive1 D:\
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Raw CID Bytes: E2-10-87-D5-A3-C2-12-B4-52-32-45-41-45-41-94-00
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Manufacturer ID: 83
OEM ID: NC
Product Name: NCard
Product Revision: 0.2
Product Serial Number: a5d0f463
Manufacture Date: 6/2015
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1) Connect Your rooted Android device via ADB.
Copy evoplus_cid on the rooted Android device into /data/local via adb
2) Give evoplus_cid executable and root privileges:
chmod chmod 0777 /data/local/evoplus_cid
3) Make sure you know which device your sd card is (mmcblk0/mmcblk1)
4) Run evoplus_cid :
/data/local/evoplus_cid /dev/block/mmcblk1 94414541453252b412c2a3d58710e2 (keep in mind to reverse order the CID pairs and skip the last zeros), check with ReadCID.exe if the CID now matches the one from Your PB626.
5) Copy the content of Your PB626 internal microSD via USB Image Tool/DD/Roadkills DiskImg or whatever program is able to do a 1:1 copy.
Have fun with Your device again and keep a copy of the microSD image somewhere safe and thank Richard Burton & Sean Beaupre for their efforts & tutorials to change the CID.
The mentioned CID and Product Serial Number are imagined. Mine are different.
This was just a proof of concept to be on the safe side if something happens to my internal microSD. I didn't check if I could resize the partitions on the microSD. That will be the next step.