https://arstechnica.com/gadgets/2022/09/apple-watch-ultra-teardown-suggests-new-but-trickier-repair-angles/

Like the iPhone 14, the Apple Watch Ultra has a quietly revolutionary aspect that went under the radar—at least until the people at iFixit tore down the device. Apple's new category of wearables is "a potentially giant step towards making the Watch more repairable," iFixit writes, and it all starts with the screws.

Four pentalobe screws on the back of the Watch Ultra, unique among all Apple's Watch models, suggested the same kind of front-and-back access that iFixit's iPhone 14 teardown revealed. But opening from the back will almost certainly damage the Ultra's waterproof gasket. And the experienced teardown team at iFixit also lost one of the band release button's springs during removal. Most disappointingly, there's not much to be replaced from the back other than the back itself and its sensor array.