I did my PE in materials and machine design, I have some familiarity with stress, metals, fatigue, etc. I'm not saying it's impossible that the OP squirted some flammable liquid in his can and blew it up, but I don't think it's likely, and it's certainly not the simplest explanation.
The simplest explanation to me would be that the stress risers from the engraving, be it as designed, or maybe cut a bit deeper than intended, possibly in conjunction with a flaw, or inclusion, etc caused the localized stress to rise above the fatigue strength of the material leading to a low cycle fatigue failure. Just because something survives the first several hundred or thousand cycles doesn't mean that when it breaks on cycle 1,001, the failure isn't the product of a problem in design or manufacture... The entire fields of study on fatigue and fracture mechanics are built around this reality.
So your supposition could be correct, that the OP put a bunch of flammable liquid in the can and happened to hit the right fuel air mixture to cause a detonation (usually has to be fairly well controlled at a certain mixture if you want an actual fuel-air detonation), but I don't think so. I think the picture very likely shows the product of fatigue and a manufacturer defect as I said above. Speculation along the lines of "YHM usually makes heavy cans so the wall on this can is probably pretty thick" don't really do much to change my thought process on this. I also think YHM will probably cover this under warranty, although it may still involve the OP waiting on another stamp.
OP, can you clear up the issue, did you squirt a flammable liquid in your can prior to this kaboom?
Edit: Whups, forgot the can actually belongs to the OP's buddy, not the OP himself.