Problems when flashing X7, hangs at 5.3 test device fails

Hello

I am trying to flash my X7.

I have tried some different images for X7, some newer, some older but I always have the same problem.

When I go into recovery mode and try to "restore" via the rockchip batch tool 1.8.
My X7 shows up green as "5.3" and then start immediately with "testing the device" and then it says "test device fail".

I would like to start the flash procedure from scratch but I have no idea how to do it.

Anybody can help ?

Thanks !