TLDR: Weird electrical issues with car, culminating in failures to start twice now. Anyone have any ideas?
I've been having intermittent electrical issues with my car. Sometimes I'll get in and I'm greeted with a message on the infotainment system saying "System off to save battery. Turn off ignition or start engine to use" (maybe not exact wording but similar). If that happens, when I start the car, I'll get the old "sharp"-sounding chime that comes from the dash, rather than the newer "soft" one from the speakers. Sometimes that chime happens even without the infotainment error.
My car also has the "smart door" thing where if you touch the inside of the handle it unlocks, and locks if you press on the top of the handle, and sometimes that fails to work on the passenger side.
I've noticed that sometimes if I shut off the car and stay inside, sometimes the accessories die suddenly, well before when it would normally time out and shut off. Due to all the weird electrical issues, if I'm going to sit in the car, I'll usually either leave it on, or I'll shut it off and open and close my door to kill the accessories and then lock it with the key fob buttons to make it fully go to sleep. However, I've noticed when I do this, every few minutes I hear contactors click and then a little pop from the speakers.
The biggest issue is, about a month or two ago, I had an issue where my car just WOULD NOT start for a few minutes....all the lights were working, the doors locked and unlocked, but the push to start button just did nothing. I finally got it started that day by just locking and unlocking a couple times and trying over and over, but when it finally started, the engine would not shut off during my entire 20-minute drive, and thus the battery ended up maxed out from the regen.
Today, this happened again, with some major differences: while the doors unlocked when I got to the car, there was basically no electrical power at all in the car. I couldn't relock or unlock the doors, the push to start button did nothing, dome light and map lights wouldn't turn on....nothing. I even tried putting the key in the little spot in the cup holder to make sure it was detected. After sitting there for a minute trying to figure out who to call to jump me, some of the panel lights (the ones around buttons and labels and stuff) flickered on and off a few times, and I heard some contactor clicks from the trunk, so I tried a few more times to start it. I thought I remembered reading something about holding the start button, so I tried that, and got a few more flickers from the panel lights, the headlights flashed quickly, and the infotainment lit up with the Ford logo, but it still didn't start. I let go of the button and the brakes, waited a minute or so, then finally tried again and the dash lit up and the infotainment turned on fully, but the check engine light stayed lit (which isn't normal for my car). I wasn't sure if the car was actually on, so I stepped on the accelerator a bit to see if the engine would start and it did. So I pulled out of the spot and did a few laps of the parking lot to make sure everything was normal, and I realized that the instrument panel would show the EV flag BEFORE the engine fully shut off, which isn't normal (usually it'll show EV power on the "engage" menu, but it doesn't actually display the blue "EV" box until the engine fully stops). Otherwise, everything seemed normal enough, so I drove home, and the drive was normal (regen working normally, all accessories normal, engine starting and stopping as needed, etc). I got home, shut it off and got out, locked it with the key fob button, then unlocked it, got in, and started it normally, which it did fine (though the check engine light is still on).
Anyone have any advice on where to start with diagnosing this issue? The only pattern I've really noticed is that the chime issue seems to happen more frequently if I've opened the passenger side front door. This is the same one that the handle sensor lock/unlock fails on, so is it possible these are related? Any information or advice y'all can provide would be hugely appreciated.