The 00 code usually means a totally dead system. Power is getting to the motherboard to light up the 00. Otherwise, it sounds like the CPU is not working at all.
To be sure, you need to plug in the 24-pin motherboard power, the 8-pin CPU power, the 8700K CPU, and some memory. I take it that you are using the integrated CPU graphics because you don't list a graphics card. In that case, the back panel HDMI port is correct for the display. That should get the rig into bios. Storage - hard disk or solid state disk - will be needed for the operating system later.
Some suggestions:
Set the motherboard on the black inner box of its packaging. That box has a little conductivity that helps dissipate static electricity that can harm lots of stuff.
Reduce memory to one stick. See the user's guide for which socket is preferred for a single stick.
Dismount and remount the CPU. Double check for bent pins in the CPU socket. Also check that the heatsink is firmly mounted but not so tight that it distorts the CPU in the socket.
A heatsink, with fan if that's what it uses, is ALWAYS needed whenever power is put to the CPU. Booting is a busy process that works the CPU rather hard. The temperatures that happen without a heatsink are more than a little stressful. The CPU may throttle back voltages and clocks to protect itself, but don't count on operating it that way.