This sounds like a not uncommon problem with modern keypads
and micro-switches : contact corrosion or wear.

I have disassembled keypads and microswitches and gently cleaned the
carbon-coated and PCB areas with contact-cleaner and sometimes stroked
the contact areas with a very soft lead pencil. It usually works - but not
for a day longer than ever...

WD-40 is not indicated, it will loosen up mechanical sludge, but
more likely do the opposite to contact areas - it is o i l -based !
Where WD40 has been applied, a re-do with switch-cleaner
or other alcohol-based cleaner might be indicated - but only for
the brave or initiated. (Don't waste best Scottish beverage
on the attempt - you might need it for yourself...)

Michael UK