[NikFu S.]

Correlation doesn't equal causation but if the hill was the problem jacking up the rear of the car would likely allow it to start, even if for a moment due to residual fuel in the lines. I think this would indicate a failing pump or fpr.
There are too many causes for non-starts and they range from the embarrassingly simple to the prohibitively expensive.
If this were my car the next step I would take is to jump the fuel modulator, instructions can be found in one of my recent threads. I'd link you but I'm on my phone, nav is difficult.