Using the following sources you can resurrect your bricked UMI eMAX mini. No tutorial yet, sorry.
This tool is safe to use.
Qualcomm drivers for both x86 and x64 Windows systems: New_Qualcomm_Driver_8936_20150414.rar
eMAX mini Software Download Tool: 6FA4-ZP0-P5002-Flashtool.EXE (This tool has its own guide in the Help section. There's a driver installer in the tool as well. It will install the mini_001_10/19/2015 - Build number: LRX22G version ROM on your phone)
To put your phone into downloader mode for flashing:
Power off your phone (if your phone is in boot loop, you can power it off by keeping pressed the power button for about 10 seconcs)
Connect your phone to USB and immediately (after the vibration) press and keep pressed all the 3 side-buttons until you see the Warning screen (just wait for the next vibration if your screen doesn't work because incompatible ROM is installed).
Long press the Vol-up button until the screen gets dark (If your screen doesn't work, watch the device manager and releaase the button when the HS-USB QDLoader 9008 appears among the COM ports).