The "four rooms on a breaker" and the re-trip with a flash, along with the routine shutoffs owing to rewiring the poles... together completes the picture.
Four rooms is an enormous load for any circuit, especially when one of them is a kitchen. And this is a smaller 15A circuit. And there are "safety power strips"** and as such, I suspect there are also other loads which you did not mention or are unaware of.
In any case, this circuit is certainly maxed out.
It's also possible the fridge is getting old and tired, or even having a ground fault.
So here's what we know. When you reclosed the breaker, you got a flash, "foof" and retrip. And you did it again (bad move), same result.
Certainly it's reasonable to assume that if you manually shut it off, and later turned it back on, it would trip again. Ditto if you shut off the whole panel/house. Ditto if there was a power outage, and not all outages have to do with scheduled work. (This assumes the freezer has warmed up a bit and wants to cycle on: if the freezer is sanguine, it may not trip.)
This is an immediate, big-flash, magnetic mode trip, which only happens at 5 to 10 times a breaker's thermal mode current rating. What would cause that? Inrush current at startup - this is a characteristic of most motors, most lightbulbs, and most power supplies. And this explains why you can power everything up if you start each one at a time. The fridge's current draw is dramatically lower once its motor has spun up, so as long as you introduce each inrush current one at a time, you are OK.
Inrush current is why the breaker's magnetic trip rating is so much higher than its thermal trip rating. A great deal of it is tolerated.
On power restore, everything restarts at once and they are stacking to cause a magnetic trip. This shouldn't happen. Either one appliance is defective and causing an extraordinary startup load, or you just have way too much stuff on this circuit.
Inrush current applies every time an appliance cycles on, e.g. A fridge will turn on and off intermittently as needed. If two big appliances both happen to cycle at the same time, you will get a spurious, unexplained trip.
What you really need is a dedicated circuit for fridge and for freezer. If the landlord is fond of removing the panel deadface, this shouldn't be too much of a challenge for him, I see 3 empty spaces.
Or it may be time to replace an old fridge, or at least its motor's start capacitor.
Figure out which loads are on which breakers, and how much each load realistically draws... and move things around so they are sane. A Kill-a-Watt will tell you what any appliance or power strip draws. Unfortunately I don't onow of a device like that which will tell you about inrush current.
** "safety power strips" are not a thing, by the way. Strips are receptacle splitters, to give you 6 sockets where you had 2. Used well, they can be safe, but all the loads on them together add to the demand on the circuit, so it is exactly the same as if they were plugged in directly. So if the notion is "they let me plug more stuff in", that is only true if all their power draws add up to a sensible number.
As far as safety, they certainly add anything but that, and they are probably the cheapest and most shoddily made part of your entire wiring system (unless they're Tripp-Lite, then nevermind.) Perhaps they mean "as opposed to this other unsafe power strip".
I think what you are trying to say is that you momentarily lost a phase. By the way there are 2 phases in you panel usually labeled A & B. Each one will read 120V to the neutral (ground) and 240V when measured phase to phase.
The momentary loss just might be a power company failure, but you might also be losing a phase in the panel. It might be just a loose conductor feeding from the meter to your panel or you might have a lose connection where the main id attached to your bus or your dryer breaker may not be making good contact with either its conductors or bus. Or like you said you may have a main going bad but that would be the most unlikely situation.
Open your panel and look for any discoloration or burned insulation around the breakers. When the dryer is running feel its breaker and the main and see if they feel warmer than the other breakers. If you have one check them out with an infrared thermometer. If you have a voltage meter you can test across the breakers and see what kind of voltage drop you are reading. It should be around .05 to .03 volts. If its reading somewhere around .1 to .3 volts you are reading a higher resistance in the breaker than usual and may be damaged. Also check the conductor landings on all breakers including the main beaker and make sure they are tight. There will be a lug torque chart on the panel door if it hasn't fallen off. If it's missing you can go on Sq D's website and they will have a lug torque chart.
I am surprised that if your utility company came out they didn't mention whether they had a phase loss or not since they should get an alarm and record if that happened. If you think this is testing is a little over the top;
This is the end result of what might happen.
So good luck and stay safe.
Best Answer
If you haven't yet turned them back on for some reason, it's most likely just an oopsie. There's what I call Face-Plate panel covers that don't recess or lock themselves around the breaker block nor have any lip that seats around the panel box (dumbest things ever). I & many others have been caught off-guard by these swinging or just shifting enough during removal to shut-off a whole side of the panel. You really don't notice the simultaneous click if you bang the cover or are talking. Maybe you or he hit them with your elbow, but circuits don't just suddenly crave attention.