need some help from the online honda community...

i have a 2000 civic ex which just got a b16a2 from a 2000 si. the b16 started multiple times in the donor car, no c.e.l.s. i am using the b16 harness because i didn't want to splice the distributor plug; which to my knowledge is the only difference between the ex and si harnesses.

the swap is done, but the car won't turn over, the fuel pump doesn't even turn on, it appears the starter isn't even getting a signal.
all plugs/connectors have been triple checked
all three grounds are on
battery is charged
all fuses in both fuse boxes have been checked and are good

plan for today is to try another ecu and test light the wires/harness

any knowledgeable input is greatly appreciated ; is there some difference between the ex and si harnesses that i am not aware of, or something else i have overlooked? anything else i should do?

(additionally, i realized that although there is a strong honda "community" where i live, i don't know of any other swaps like mine; lots of obd2 into obd1 swaps, swaps between gens, but no one else that has put a 99-00 b16 into a 99-00 ek/ej. anyone have experience in this?)