I flashed the wrong bootloader and have hard bricked it.
I have found it with different names, Eweat/Vontar/Voxlink M9, it has 1Gb (or 2Gb?) of RAM / 8Gb of EMMC and android 5.1.1.
The emmc is a Samsung klm8g1wepd-b031, see attached pictures. I have tried shorting all pins to ground, and all adjacent pins, but the device does not get detected at all.
Anyone can help, please?