Engine swap from golf 1.4L tsi to 1.2L tsi. Car wouldn't start. Need advice

[rain]

Hi, so I'm working on my 2010 golf, 1.4tsi 118kw engine, it's running very rough on idle, and i've replaced everything from sparkplugs, to coils, to intake air regulating flap, oil cooler(coolant mixed with oil but not a headgasket issue) and the turbo, but the problem still remains. I was planning on checking the injectors too but it's in such a ****ty place, no clearance unless I remove the intake manifold(which I thought would be easy enough, but I have to remove the intercooler too to get 1 bolt out of the intake manifold, and I might even have to remove more stuff to have enough clearance to remove the intercooler, I can be wrong tho, but I tried). Anyway, I found a same model golf with more than half the mileage of what's on mine but the engine is different, a 1.2L 77kw engine, so I made the decision of just swapping the engines, rather than putting any more work on the other engine. All the wirings and fluids are done, but I can't seem to start the engine. I checked my fuel, all good, for spark...I think I'm not getting spark, I used a timing gun to test if I'm getting power on my coils and it seems like I'm only getting a response from no3 coil, and nothing else. Should I replace my coil pack? or am I even in the right track? I'm thinking maybe it's an ecu problem? cos I tried using the ecu that came out of the 1.2L engine but I'm having issues with the immobiliser, so I used the original ecu that came with the car, I'm not sure if it's compatible with the new engine tho because the new engine doesn't have an intercooler. Would really appreciate any advice. Thank you very much

[MIG]

Is the 1.2L out of the same year golf? What are the two engine codes?

VW Golf 6 - Wiring Diagrams -vw-golf-6-wiring-diagrams-eng.pdf

Cross-check your harness wiring between the two; the ECU will need to stay with the engine it came from, as the software will be specific to the 1.2L (Are the two ECUs the same part number? ) depending on the part number, it depends how you can do the immo matching.

If you have a scan tool, you should be able to do output tests on the ECU; this will allow you to verify that your wiring is good by doing output and checking with a test lamp and each component.

Another thing to check with the scan tool is to see if you get an error on the camshaft or crank position; that would explain why you have no spark.