Q: Replaced the transmission and now car won't start

I replaced the transmission a month ago on my car, and I have just started hesitation at lower speeds. I switched out the spark plugs, but the hesitation persisted.

It was giving a code of P025A, which online reads as "fuel pump control module circuit open". I don't have a reader myself, so I scheduled an appointment at the mechanic for a definitive diagnosis of which cylinders were missing, as I was told it was likely a bad coil or possibly bad coil insulators. But, my mechanic can't get it in for a bit, and the car died today.

It dropped out of cruise on its own, the TCS light got stuck on, then it threw a MIL, followed by another Check Engine Light. It seemed to get stuck in 2nd or 3rd gear, as it had no power off the line, but did eventually get up to highway speeds.

When I got it into the driveway, I wanted to make sure it wasn't the transmission again, so I tried to go into low gear and it did the same thing. Then, I put it in neutral and tapped the gas. It revved up to ~2100 RPM, stayed there, and then after a half second it revved up higher to about 3100 RPM. All from a brief depression of the accelerator.

I feel like these are all pretty isolated symptoms with the only common thing being the PCM. I just went back out to the driveway and the car won't start all now (no clicking, no turning over). What can I do to fix this?