blank screen after setting Secure boot ON and disabling legacy

Hi,
After switching to secure boot with my Wyse 5070, I have been unable boot or even see the splash screen, others was able to solve this by pluging VGA monitors but Wyse 5070 only have DP and USB-C 3.1, tried USB-C to HDMI adapter but it didn't work.

Also tried removing cmos battery and putting it back, tried setting jumper to 'CMOS CLR' but all didn't work.

How can i solve this please?