Hi mate it snapped by some overgrown ape just hanging on it that little bit too much
As per pic it has snapped just below the tapered groove so you couldn’t have gotten anything into it to tack onto really.
If I’d have not tried drilling it and using a tapered stud extractor myself he could have drilled right down and double helicoiled it, it’s just because I’d snapped a tip of the extractor in he said you can’t drill them out without using some high strength drill bits that cost silly money and even them are throw away drill bits by time you’ve got the broken piece out so for the sake of trying it today and me being able to get out working he did one helicoil and we think it’s nipped it hopefully!