First thought would be crankshaft or camshaft position sensors - even stretched chain/belt which can lead to sensors being out of sync.
However as the engine fires when sprayed with brake cleaner then I would look for any fault codes, engine compression, even oil quality can affect starting (washed down with fuel, etc which lowers compression)
Battery voltage, earth points (leads and connections) in fact there are so many other factors that could affect the engine not running.
Start with the basics and go back over your work as it may be something simple that has been overlooked.
Let us know how you get on and what you find