Morning surprise and how it has been resolved
After night of printing this creation held tight to my MK4S printer. I was lucky that there was a way to remove it from extruder by disassembly of fan holder and nozzle. It was still hot but solidified.
To remove it from the nozzle, I put it into hot air oven with 185 Celsius temperature for about an half an hour with wires protected from direct heat exposure by aluminium foil. Clot softened and I was able to cut it with knife and pliers until nozzle uncovered.
Then it was necessary to clean nozzle thread from plastic residue which got into it using a knife (no photos taken).
Printer is now back at work performing like before even with slight damage shown on the last photo.
RE: Morning surprise and how it has been resolved
Oh my god, best I think to change the nozzle, maybe it got blocked or what was the cause.
Is there a fire risk in this scenario, I print mostly through the night, the 3D print shop is adjacent to my bedroom, I do not want to be cremated until I pass on. LOL
Very little risk with Prusa or any modern 3D printers. There were some printers about ten years ago with acrylic frames that did have a tendency to halt and catch fire but I've heard of nothing recently.
The OP had a classic 'Blob of Doom' - the OP found his own solution but search for that description to find how others have dealt with them.
Cheerio,