bang-bang

[spannerrash]

I would start by fault finding the injector first. Remove the fuel pump relay to prevent any more fuel contamination or unplug the injector.

I doubt very much that this will be an injector fault. They are simply solenoid valves, a coil of wire, and usually fail with an open circuit fault rather than short to ground.

I would initially suspect a fault in the ground wire of the injector. Hopefully this is not a fault with the ecu permanently grounding the injector. An injector test noid may be useful to aid with this.

You are going to need to do some multimeter or at least test light fault finding from this point on. Is that something you can deal with?