HP-28S Keypad Issue

[brouhaha]

(03-13-2024 09:34 PM)BitWiz Wrote:  However, I am able to get the bottom row to work perfectly and even pass the keypad test if I press any where on the bottom plastic frame of the LCD.

The contacts between the flex circuit and the logic board are pressure-fit with a foam strip. The car on zed contacts on the flex circuit can wear, and the foam degrades over time, eventually not providing enough pressure. AFAIK the only way to fix it is to take it apart, clean or refinish the contacts, and replace the foam strip.