Solar well pump troubleshooting on the lab

I'm not exactly sure where best to post this, but I won't submit it as a BB to keep from complicating things.
If it's worth some oddball points, fine too, but I'm primarily trying to go on record as to what is there for the next person to be able to find.

My family was recently staying at Allerton Abbey, as SEPPers.
The pressurized water system up at the labs stopped working.
They're a little short-handed for bootcamp labor and probably are prioritizing tasks to better prep for the winter.
No one who was involved in the original construction of this system, is available, and probably no longer at Wheaton Labs.
They don't have, or don't have access to any documentation of this system.
I volunteered to look at the solar pumping system, to troubleshoot and at minimum document it for future users.
Everyone in my family likes water 😉

This is not a complete documentation of the system, as it wasn't necessary to get to the failure - more on that later.

There are 2 strings of solar panels feeding the combiner box near the panel mount. The lower 3 are the same models and are in series. They are about 335 watts each. The top two are in the other series string, they're newer, and probably a higher power & different voltage than the lower ones, but that turned out not to matter, because that part of the system is working fine - there's solar power available at the charge controller, move on to the next part...

The charge controller was a few firmware revisions out of date, but the Bluetooth pairing code is on the sticker on the unit. Connecting to it immediately started one of the updates from my tablet (I own 2 of this same model charge controller).  After updating, the unit showed briefly, a slight charge current on the battery pack, then it dropped off to zero. It shows a battery capacity of 100 Ah, which may or may not be accurate, but it matched the battery monitor display on the side.

I say it may or may not be accurate, because that's part of the initial configuration process, to tell the system what size battery is connected, and the shunt that is being used, is likely a Renology brand shunt (not a Victron shunt), and it plugs directly into the battery monitor (shunts periodically need to be recalibrated to stay accurate, because they will drift over time).

The biggest reason for suspecting a battery size mismatch, is the physical size of the batteries that are barely seen from above, without taking the system apart. There's a Daly brand 200 amp BMS, sitting on top of a wooden separator that mostly covers the batteries. From the visible edges, it looks more like a set of 8 cells, in the ballpark of 280 Ah capacity, and incorrectly wired as 2 strings of 4 batteries, so they could get by with only one BMS. Unfortunately, that also means that there really isn't any monitoring of the battery health, but it's probably still at least greater than 100 Ah. If the BMS and the battery monitor are both claiming that the battery is only a 100 Ah battery, the solar charge controller won't keep charging it past that point BUT even THAT shouldn't keep it from working at all, so move on to the next part...

The label on the BMS claimed that it had Bluetooth as a feature, but every Daly BMS I've ever seen that supported Bluetooth had a plug in dongle for it, and the port for that was empty. The Daly website also doesn't appear to list this exact model BMS as a supported model anymore, but STILL that's NOT the root cause of the system failure... If the BMS wasn't working, it wouldn't show voltage from the battery positive to the ground terminal, so either way, the BMS is NOT the problem...

There's 14 volts at both the fuse panel and at battery system main power switch, which is also what's wired DIRECTLY to the pump (There's NO external fuse or breaker on the pump supply line!). According to the pump mfg website, this model pump is internally "protected from overload", and has an internal pressure switch, which is supposed to turn off around 55-60 psi.

The external pressure gauge shows only 25 psi, and the motor leads show proper voltage, but the pump doesn't turn on...

I would guess that the internal pressure switch is not working properly but without further disassembly, there's no way to tell, and disassembly would probably void any warranty remaining, which is supposed to be 4 years (according to the website), and according to Paul, "this is a NEW PUMP!", so I won't try taking it apart.

I'd recommend an external circuit breaker in the future version, so the motor doesn't have to destroy itself to protect from any overload condition. Ideally a 20-amp resetting breaker inline, instead of a fuse, because it's not in a particularly accessible location and a breaker will mean less man-hours to keep the system running