Sounds like the feedback circuit has failed and is so crappy that there is no other limiting circuit so the primary side switched mode controller is running flat-out. IMHO its of very little interest as although its not a very common failure mode, one cracked track or open-circuit resistor is enough to cause it.
Why not tear it down yourself and post about it here? If you don't feel up to doing a video, good photos and text are IMHO actually preferable as they take a lot less time to look at, and are easier to study in detail. If you do do a video, *KEEP* *IT* *SHORT*' - 5 minutes max.