2004 sv650 wont start after swapping engine+throttle body into another frame?

So lets get started. SV650S 2004 (2nd gen). bike doesnt start anymore

• removed engine from one frame, placed it in the other. so far so good.
• replaced oil and cooling liquid (shouldnt make a difference but anyways).
• fitted first throttle body -> upper throttle valves stay open at almost 90 degrees vertical.
  • fitted another throttle body -> did the same thing
  • used different ECU -> still did the same thing on both throttle bodies.
    • may i remind you that both the ecu and throttle body used in the first place worked fine when still in the old frame.
• tried starting it anyways with jumper cables and an old battery as to not damage the current one. didnt work.
  • engine cranks over, spark plugs give spark, gasoline in the throttle bodies upon removal would indicate the fuel is going into the throttle bodies without problem.
• tried starting it while turning throttle to give it some extra gas.

i'm kinda at a loss for what to check for next. fuel primes fine. any suggestions?