A loot at the picture below should tell you all you need to know about why this replacement John Deere style rectifier-regulator failed. Typical of low end Chinese goods, an effort was made to make it look like the original, but there was apparently either no comprehension of the design, or they just didn’t care. You have a large, thick aluminum body that is supposed to act as the ground and the heat sink. So look at the orientation of the high power semiconductors on the board. That heat sink isn’t really providing much benefit, is it? There’s nothing in contact with it, other than a ground wire… the parts were potted in a rubber compound that insulated them both electrically and thermally. No wonder it fried after less than 10 hours of operation.
How difficult would it have been to mount those parts on the opposite surface and put them in contact with the aluminum case, perhaps with a dab of thermally conductive grease? The cost may have increased by a few pennies, and you’d have a fairly reliable part. So either the manufacturer intentionally produced a defective design, or they simply had no clue what the hell they were doing. I’ve seen a lot of that coming from China. I’m sure there are a lot of very sharp, conscientious engineers and business people in China… whoever produced this piece of crap wasn’t one of them.