2017 21.5” iMac 4K completely died during a software update. Apple Store claims corrosion is the issue and that it requires a $500 logic board replacement. Has anyone seen this before? And is this actually corrosion or something else? Any advice would be appreciated!

Jun 2021 ⋅ ⋅ ⋅ #2017 #500 #21 #5 #4