Engine cranking but not starting?

So car was running very well previously but I had some issues which used to happen only going up a steep hill, I could get a big bang which I think was a misfire. So I could occasionally connect an obd2 scanner and I realized I had fuel pressure regulation outside specifications. I changed the fuel filter and was planning to change the hpfp but I also wanted to check state of the fuel injectors, so I opened up to check on them. When I closed the car, it started revving up and down and I realized I had a leak. So I attempted about 3 times fixing the air leak by trying to close tighter. Every time I finished and tested the car, it could start but could rev. I tried again the 4th time but this time I was putting a new intake manifold gasket and also changing the ignition coils. So I finished and tried to test my work if revving had gone, the engine didn't turn on but could only crank. I thought it was the coils, replaced old ones but nothing. Used different batteries but to no success.

Mechanic's Assistant