Bricked devolo WiFi pro 1200e


I just tried to flash my 1200e with the 19.07.1 image on the website.
I followed the instruction to flash properly, but now, after flashing, I can't get the device up again. The blue LED on the device ist just on. Nothing else happening. I can't recognize any DHCP requests in my Windows Server. Waht should I do now. ?

Here is the log of the flashing:

root@ap:/# sysupgrade -n -F /tmp/openwrt-19.07.1-ath79-generic-devolo_dvl1200e-squashfs-sysupgrade.bin
Image doesn't have a checksum.
Image check 'platform_check_image' failed but --force given - will update anyway!
killall: watchdog: no process killed
Sending TERM to remaining processes ... uhttpd udhcpc avahi-autoipd ntpd Connection reset by port 22