Chosen Solution
I know the version I have (Casio fx-115 ES Plus 2nd Edition) is solar powered, but I thought that it could at least store power or use it’s battery when it’s not directly under a light source? As of now, it won’t turn on unless it’s directly under a light source…
It is possible that this model doesn’t have a battery. Many calculators are 100% solar powered. However, if this model does have a battery, the battery is probably dead and needs to be replaced. These batteries are usually not rechargeable even though there is a solar panel. Over time, the battery will die. If there is a battery compartment or cover on the back, then it is simple to replace the batteries. Otherwise you may have to take the whole thing apart (assuming it has a battery in the first place). Hope this helps.
