almost wasted time!
I can not stress enough.
DON'T USE A MULTIMETER!!!
multi strand wire used on all cars can be almost completely broken except for one strand so down to less than a mm of connected wire and a muti meter connected on that circuit WILL show battery voltage,
12V or better.
Bur even though it showing Bat V on the meter it just will not carry enough current to do anything useful.
So Voltage tests are worse than useless,
And they're miss leading.
I'm going to quote Dan Sullivan he inventor of "Load Pro" leads.
there are only three things that can ever go wrong with a wiring system.
Seriously Look him up on You Tube,
even if you don't buy his lead set his lecture for want of a better word will help very much in your situation.
Now I own a set of his leads and wouldn't be without them now.
Prior to this I used the jumper wire/12v bulb system.
and this is what you need to be using.
Your meter is showing 12V now connect up a jumper wire/bulb holder and earth lead and see if the bulb lights,
divide that by 12 gives just over 2 amps,
and if there's extra resistance from say a corroded connector or a wire down to 1 strand you will have exactly the sit your in now.
But I'm thinking you have more than one fault.
the injectors are powered to battery voltage when key in on,
the ECU pulls the other wire to ground so triggering the injector.
So when you had your accidental injection fire the wire from the injector connector that goes to the ECU was shorted to ground/earth when you manipulated the harness.
There is no other explanation.
Trace that injector ground wire,
the one that doesn't read bat V back to the ECU,
there WILL be a short somewhere along it's length.
I've seen them as small as where ONE strand of wire is exposed from the insulation.
Or disconnect the ECU and the suspect injector,
connect the bulb across the injectors two terminals and use more jumper wires into the ECU connector plug to power up that circuit directly to the battery,
This is now an independent from the vehicle circuit,
only powering up 1 injector circuit.
bulb should light up,
then wiggle test until the bulb flickers/goes out,
and your short is where you've wiggled.
Volts are a next to useless test,
Amps are what actually do any work.