Not Accessible Sdcard On Mi2

Jan 27, 2013
I have a problem on Mi2. I was going from 5.6.25 (separate partitions) and updated to 5.12.4 via updater. Everything looked fine but after reboot I've got stuck on the fastboot logo for more than 1h. So I pulled out the battery, reboot didn't help. Then wiped all data - no change. So I switched to the other system partition (with older MIUI version), it worked but there is no working internal partition (I can see it as "Phone" but when I wan't to add something there (create a folder etc.) the Explorer freezes. Wipe/format sdcard is not helping.

So I'm not able to update the ROM, not even via OTA. MiFlash also stopped to detecting the phone (it was OK before). And ADB says: failed to copy '' to '/sdcard/': Read-only file system (and it cannot connect to my phone)
I have no clue what to do now... Could someone please help?