I had a nearly identical experience when I inherited my grandfather's old coffee grinder. The buttons made no sense, and none of the manuals I found online were for the exact model. After wasting hours on random sites, I finally came across www.manuals.online/ — and to my surprise, they had a scanned copy of the exact user manual I needed. What I liked is that it's not just PDFs; people leave comments and troubleshooting tips that actually helped me figure out how to reset the grinder. They cover a huge range of devices, even obscure ones from decades ago, and the interface is straightforward. I’d highly recommend checking them out.