Fixing old G3 and G4 laptops
Your G3 probably has a dead motherboard battery.  Depending on the model, they are usually not that hard to replace and cost between $2 and $30. 

As for the G4, I'd say physical damage from the fall is a pretty good assumption.  Since it sounds like multiple components are damaged, it may not be worth the effort to fix unless you just like to tinker.