Man, that sounds like a nightmare! The keyboard acting up with missing numbers and letters is the worst. Honestly, I’d just replace it at this point, especially if it’s causing that much trouble. If you’re thinking about getting a new one, check out these compact keyboards:
https://crytech.club/collections/mini-60-70-80 . They’re sleek and don’t take up much space but still give you great performance. And as for the cooling fan, Microcenter giving you that “proprietary” line sounds like classic upsell BS!