That might be true, but let's be realistic, the material seems like plastic and if you look at the analogue board pictures above, you can see the other corners look alike, but the bottom left corner is out of shape, this leads me to believe that it was made to handle certain amount of heat and on that one corner, the amount of heat exceeded the operating temperature and it just melted. So something happened that should not happen normally.
If your meter will read really low resistances you can measure the shorted rail in different area's or the board and the reading should get lower the closer to the shorted component you get. I haven't ever done this personally but have seen it done online a few times and it seems to work
Other than that what you have described should work in most circumstances (It's what I would usually do on modern boards) however it will not work on really really low resistance shorts (e.g solder bridges)
So well, not so good as it turns out. As soon as I slotted the batteries in I heard a little "click" noise from the part of the board near the power button or thereabout. Removed the batteries of course...
I got investigating, and there is a short on the main rail! Almost everywhere... that annoyed me a lot as I was very careful but then again... small mistake?
So I started to remove all the caps I replaced (well the SMT ones, I can't see the bigger ones being a problem!) and test until none was left and... no luck, still shorting.
So I think I'm going to also remove the 4 SOIC I installed, and then ----- grrrrr remove all the patch wires. And I still don't know if it will fix it, as I'm not entirely sure the short wasn't there in the first place! How *annoying*.
Next is to try to find the short, I got some freeze spray, and a bench supply of course, so I'll try to put 3V with increasing Amps into it and hope I can see something heat up.. unless someone has a better suggestion?