The ASV's injector timing is set by the toothed belt, so bump-starting may be possible. I'd hate to do it, though, the strain on the clutch and gearbox of trying to turn over a 19.5-1 compression ratio will be fierce. Cars with ECU's are generally a bit dubious to bump-start, as you risk any special "start-up" functions within the ECU not being engaged.
However, if your starter is not turning over the engine then generally either the starter is shot or the battery is not man enough. One other possibilty is that the earth straps connecting the engine to the body amd battery to body are worn or the attachments are corroded, which will limit the current that can be applied to the starter. Check all your earth straps, the one from the battery to the car body and those from the body to the engine/gearbox. The engine is on rubber mountings, so the earth straps are the only way the circuit can be completed. You should look for corrosion at the mounting points at both ends of each strap, and to see if the straps/cables are fraying. As I've already said, the starter needs a lot of current, which means you need large conductors with good connections.
I did once have the battery strap simply break on a 1.9 TDI
Ibiza. Park up at the supermarket with no difficulty, come out to take the shopping home and nothing. The clue for me was a complete lack of electrics, which hinted at a failure at the battery.