I'd jumper the fuel pump to battery / ground and go from there. Look at the pump, there will be a + and - on the pump. I think the fuel pump relay is in the drivers under hood box ( you have to remove phillips screws not just flip the fuse lid )

With this system the car will crank even if the DAS X "chip in key" antitheft isn't working. I think it will still start but stall after a second or two., If you swap engine computers with another car, you must use the magic box directly behind the instrument cluster and key that belongs to both boxes. I use a spare ring antenna to work with the donor boxes key and the mechanical key to turn the lock.

The buzzing throttle is a sign that the engine computer is waking up and doing something.

When checking for voltage in this situation, don't use a digital meter, they don't load the circuit enough and can pickup stray voltage. Use an incandescent test light ( not LED either )and if you want to , the meter in parallel.

Someone else had an issue with a common ground corroding and taking lots of stuff down.