Open it up and pump plenty of glue in, then bind. It really should be replaced though if it's under warranty and bought from a genuine retailer.
Not sure it would. It's the kind of damage that a retailer may very well say is caused by not knocking in properly... thus stopping them needing to replace it.
Personally I would try to refrain from opening it up too much as the wood may break off - the lamitoe idea might work the best, then you can glue it from the inside once you have cut the line fore the insert.Looking forward to seeing what you do with this - I have to admit it doesn't look good - possibly a rather short life expectency...
to be honest it will not last long now but lamitoe and a lot of tape would hold it for a bit !