I tried to flash openwrt. Booting into Medkit fom USB worked fine.
sysupgrade killed the terminal session and probably failed.
Now, Turris boots into some tftp-mode on WAN port. It gets an IP address via DHCP and requests AC1203B9.img using tftp. Tried to serve all kind of files, but none made a difference beyond that point.
Any advice?
Thanks.