Check your battery. Be sure that nothing has been
spilled in or on it. If spillage occurred, remove the
battery. Take apart the unit carefully. Note how the
keyboard and display are assembled. Some models
have separate key tops, so draw a diagram of the
keyboard layout. Clean all parts with rubbing alcohol.
Make sure that all parts are clean and free of dirt, oil,
stains, and grease. Assemble taking care of the display,
as some models use a 'zebra strip' to connect it to the
logic board. These surfaces must be clean, or the calc.
will be rendered useless.