So I'am fixing up an rx-8 that has given me trouble since i got it without an engine. The first engine we installed tryed to start up and the everything was fine except the engine with its low compression. Now we took it out and managed to get another engine which was in a crashed rx8 2004 however, i connected the battery terminald wrong and the clutch lost its pressure so now the car wont even try to turn on...we suspect the computer got blown (i also got a new starter for the car) but I replaced the computer N3H6 18 881E with N3H6 18 881K

 

i have an 881j sitting in my garage. its from an 04 m/t. i think swapping any ecu will need reprograming by a dealer but not 100% sure

 

what do you mean theres no clutch pressure? it has nothing to do with the battery or ecu. first start by checking that the pedal bracket isnt broken, its a very common issue. i think mazda has a tsb on it. a few vendors sell a re enforcement bracket for the pedal but its easier and cheaper to take it out and weld it. if the pedal is good check the slave, its a pita to bleed