Game consoles tend to have a weak spot or two that will take certain units out sooner than they would due to normal parts aging. In the case of the Wii U it’s the eMMC storage IC with the console’s firmware and any user data that likes to keel over, with the SK Hynix variant reportedly developing faulty cells much sooner than the Samsung and Toshiba chips. If you want to check the health of these eMMC ICs in your Wii U, you can do so easily now with the Wafel Installer project by [zer00p].
This doesn’t take much more than navigating to the wafel.xyz URL on the Wii U to launch the installer on any (unmodified) Wii U, or alternatively starting it from an SD card if you’re running a homebrew-enabled console. This can also install the Stroopwafel CFW, ISFSax and the Aroma homebrew environment, but the NAND testing option in the installer’s menu is what you want to select if you’re not into homebrew or have already cracked open the console for said sweet homebrew action.
All of this is covered in this video by [FunkyScott47], whose Wii U’s Samsung-branded eMMC is fortunately still all fine, but it shows off the variety of tests available. Unless the eMMC is already quite cooked this should take only a minute or two, so it’s pretty good for ease of mind.
With the heavily waffle, syrup and stroopwafel-coded naming scheme for these tools we can not be held responsible for a sudden case of the munchies, of course.

Fascinating and precisely why I dont buy Nintendo hardware. A Switch 2 will be a nice paperweight in 10 yeats
10 yeats? So if you don’t throw it 10 times, it’ll be fine? /s
Clearly this was Nintendo’s fault. If only they had gone with a reputable mainstream eMMC manufacturer like SK Hynix, instead of cheaping out and buying from a random company in South Korea called “SK Hynix”. /s