elmar.faber
Hmm, damn thing. You don’t have a serial console to attach, do you? Difficult to debug since HDMI output does not work (expectedly)…
Do the LEDs blink now at least, similar to how they did with the old Stretch image? Probably it does boot but due to expected missing HDMI output and probably failing network configuration, you cannot recognise.
Please verify that the device isn’t appearing in your routers UI, e.g. as new DHCP device/client, after a few minutes. You could as well try to setup a static IP (matching your local IP subnet) before booting the first time via dietpi.txt, then trying to ping it. Difficult again if you have no other Linux system since there is no separate FAT partition that can be mounted on Windows, ext4 only 
. However if the router serves as DHCP server, this can actually hardly fail 
.
However if this still fails and definitely does not boot, I’ll create a Buster image based on Meverics old Linux 3.10 Jessie image. It contains doubled dist-upgrading to Buster, hence could be a bit messy related to old/obsolete dirs/files, but would try my best to clean up if as good as I can .