Beelink BT3 not able to run 64bit OS

[ranXeron]

I do own the Beelink BT3 and just ordered the Futeko MiniMX. Both are neat little boxes but I got one question regarding the BT3:

Since I want to install Openelec on my BT3, I did create an bootable USB stick wit h Rufus and an actual Openelec image.

Booting the BT3 and pressing F7 I then choose the stick from the list of bootable devices.  But the box always boots straight into windows.  I tried all possible settings in Rufus (GPT Partition scheme, MBR partition scheme for BIOS or UEFI, MBR partition scheme for BIOS) but no luck.

Did I miss anything?

Update: BT3 uses a 32bit UEfI bootloader - so every attempt to install an 64bit OS (like Openelec) will fail. This is kind of ridiculous, since the CPU is 64bit...