[Raion]

Serial connections.

The Octane not doing anything once plugged in is not good.

The Fuel's white light could either be that it doesn't detect a keyboard and monitor, or that its ENV monitoring is dead. You won't know either way.

They each have their own serial settings. Null modem cable needed, IIRC, the serial port initializes at 9600 baud. Definitely 8-N-1, though.

For the Fuel, I think the baud is 38400 as is the Tezro's.

Null-modem cables aren't costly.