many microwaves have safety mechanisms to reverse, or stop the turntable if it senses resistance to the turning. This is done both because
- the turntable is usually driven by a small motor with a gear reduction transmission to get more torque on the glass platter and your food, and if something resists the turning, it can damage the gear train or belt if it keeps running.
- if you have something with liquid in it and it hits a wall, it could tip over, possibly spilling scalding liquid all over and maybe surprising the person who opens the door.
In some cases, it'll just stop and then try again the next time you run the microwave. The banging on the case sometimes turning things back on suggests that either something in the turntable mechanism is awry, or that there is a common hot wire, ground loop, or possibly fuse for the light/fan/turntable.
the manual for the oven doesn't really say anything about this.
You can see generic intructions on looking for an internal fuse here
Panasonic Microwave NN CT552W has no power plug fuse ok Has it got thermal...
. Please, in particular, make sure you unplug the oven before opening anything. This is one of those devices where defeating the interlocks and having it turn on can seriously hurt you.
With regard to the turntable, in particular, it's really easy over time for exploded spaghetti sauce, spilled cocoa, and overmelted butter to have run down into the indentation in the middle of the bottom of the oven cavity. Remove the platter. Is it clean in there? Does it look like the 'this person never flosses' picture for mechanical rotors? If so, start with some kitchen cleaner and a washcloth damp (not soaked) with hot water. Let the cloth steam /warm the area a bit, wipe it down. repeat if necessary. If there's a lot of cruft built up there, that could be keeping you on the edge of safety shut-down.