Archer C7 V2 tftpd unbrick

My C7 V2 at openwrt 18.06 suddenly died. Did forget to handle wifi, did forget to use the wan ports.

Tried to reboot, got a bricked router. Does not offer dhcp, have no ip address to connect. But it responds to the TFTPD method. Here i tried first an original TP-Link firmware from 2016, than openwrt 22 factory. They must be renamed to a special name, the pc has to be on If reset is pressed while switching on, the router fetch the firmware files, do a reboot after some minutes and went back to the beginning. No ip, no dhcp, not interface, no telnet, no ssh.

Seems that the router is unable to unpack and install in both tries. Ideas?

Next try will be a baite on the internal programming port, it's ordered to go on.