Another quick check you can do is to turn the key on, don't start it (not a problem in your case hah, sorry). Then go stand up by the motor and open the throttle by hand. It's not really a TPS like normal (although there is a switch that closes at idle) - it just slides across an alternating set of contacts as it opens and fires off injector bank fires/cycles. In normal use, these are 'extra' injector firing cycles, normally supplied by the contacts in the distributor base - and they act as a sort of simple 'analog' acceleration enrichment.
So as you open the throttle, you should be getting injector fires. With the motor off, nice and quiet, you should be able to hear the injectors clicking. As mentioned above, the way D-Jet injectors hook to the fuel rail, you can pull the whole rail off the head, leaving the wires and hoses all attached - just undo the sheet metal collars that hold the injector base to the aluminum mounts on the head, give the all the injectors a little twist to break the stiction, and then gently pull the whole thing off. Set up something to catch the fuel (like the bottom of 4 aluminum cans?) and then try it again.
You want all 4 of them to be making nice little spritzes, relatively equal in pattern and volume. My last D-Jet car had a habit of having the injectors stick if it sat around for a couple of months at a time. Everything else would be fine, but they'd just be mechanically stuck a bit, too much for the electrical windings to overcome. I'd pull the rail off the head, then *gently* press on the pin/pintle at the nozzle/tip. Once that was broken free, they'd be back in business, and fresh fuel flowing through them would clean out the residual gunk that was sticking them in no time.
And then there was the one time that I spent an embarrassingly long time diagnosing this and that (I suspected the pump! or the pump relay!) before I noticed that the main power supply wire (attaches right to the 12V+ battery terminal) had come undone. Yeah, no power to the ECU, not much is going to happen. If you get a priming pulse of the fuel pump, however, then the ECU is firing up.
I did have a D-Jet ECU die once. Just driving along, 1/3rd of a mile from my house, no problem, running fine, then dead as a doornail. I checked various things, nothing seemed wrong, pump still primed, just no injector firings (either while cranking or when opening the throttle). We happened to have a parts D-Jet car then, so I swapped ECU's, started right up.