I helped one user solve this type of problem - somehow the power management was set to shut down the computer when the battery reached 99% charge. :-)
If grandpa is in another town - you might want to talk him thru installing TeamViewer - that should let you remotely control the computer and help him out of this and other jams. The Windows Mobility Center
should show you if the battery is being seen by the operating system... but since you said that the battery is showing to be fully charged, then the OS probably already "sees" it. Removing it and putting it back in a few times might clear the contacts, but I would not spend too much labor on this if the laptop is under warranty.