The customer has been using this calculator for years, religiously making sure it was sat in the sunlight to ensure the internal battery was charged, but eventually it stopped working. It's large keys and display was why they wanted it repaired so sent it to me. The investigation revealed the "solar cell" was indeed FAKE, it never was SOLAR POWERED. However, the word SOLAR was not on the case so it seems it was merely using a case built for a SOLAR cell and used a fake one to fill the space. Replacing the internal button cell fixed the problem. A fun little video showing just what is inside these cheap calculators. All fixed, the customer was happy.
{youtube}https://www.youtube.com/watch?v=ekTFK1T9F4E{/youtube}