PC error code 0xc0000225 on Imac 2017

I erased disk to fix upgrade issues. Turned computer off, went to macos recovery and got Cannot Contact Server preventing recovery options before erasing and why I erased. Turned off unit and getting PC error code 0xc0000225, preventing any bootup. It tells me to press enter or F8 and all that does is flicker the blue screen. How to reboot from Time Machine external HD backup if possible?