Well, just got my monitor back this morning (8th September), so assuming it doesn't break again in then next few hours, that has taken just under 3 months in total, if you don't count the hour I had it back a month or so ago.
Impressions so far: Definitely the same chassis, bezel around the screen is now covered in fine scratches so clearly it has been rested on a hard surface, also the mounting point between the screen and the stand is no longer flush, though it seems solid, so hasn't been put back together carefully.
However, the screen itself definitely has a new "logic board" as the menu shows software version 3.85 (was 3.65 before iirc) and I now have the option to turn "RTC" on and off (its off by default), this was the overdrive function built-in to try and reduce the effects of the 6ms motion blur, but all it really did was add an odd "pre motion" shadow, I'm very glad its now off, the difference is very noticeable.
So it now has: a totally new screen and inverter assembly and a totally new "logic board", a few more scratches than it had and a slightly wonky mounting (doesn't effect the monitor in usage).
So now all I have to hope is that in a few hours it doesn't rinse and repeat...
Fingers crossed
EDIT: Just to say, I noticed that the "neck" of the stand was at a funny angle compared to the base while walking towards the monitor. I thought initially it was due to the joint at the top, which is indeed slightly distorted compared to when I sent it off, but this was far more fundamental, it was clearly not anchored properly to the base.
Sure enough, I flipped it over and found that 3 screws looked the same but one was totally different. 1 screw fitted fine and still had its compression washer. The other two had no washer and were so stripped I pulled them out with my fingers, the third kind of fitted, but had no washer and pulled out once unscrewed by about 50%.
There was 100% no reason for this base to EVER be removed, it comes off with the neck from the back of the monitor body by simply undoing 4 large black screws. So not only have they taken it apart unnecessarily, they have clearly lost the original screws and washers.
I'm glad I spotted this as those two screws would have simply fallen out at some point and who knows what would have snapped/bent.
I have bought 4 new screws and compression washers myself and will put it back together myself, not trusting these monkeys again.
I will definitely be compiling my experience and sending it to Hyundai HQ, and I would just like to re-iterate (if it were needed) once again, DO NOT BUY HYUNDAI MONITORS IF YOU LIVE IN THE UK as the warranty service is truly abysmal.
Good luck to everyone else who hasn't had theirs back yet.