Provided you have spark during cranking, if the plug tips are wet at all, remove all of them, crank the engine to expel liquid gasoline in the cylinders (disable the ignition system to prevent sparks, have a fire extinguisher on hand), and let any gasoline in the cylinders evaporate overnight, or a day or two. I had a flooding problem with my VW Rabbit like that when testing the fuel injection system. Wouldn’t start no matter what I did. After letting the gas evaporate out the spark plug holes, it started right up.
If you have a v-style engine, this is a problem on bank one, which is the one associated with cyl number 1. There’s either too much gas or not enough oxygen in the mixture, or the o2 sensor(s) on that bank has failed. Testing the fuel rail pressure (make sure it holds when off too) and making sure the air path into the engine is open (engine air filter) are good ideas, but it sounds like you already did that. If you are certain the engine isn’t flooded, you may have to disconnect the exhaust system before the cat as a test. If it starts then you probably have a clogged cat. Sometimes you can just remove the pre-cat o2 sensor to accomplish that. Once you get it running again, measure the fuel trims and report back.