Thank you everyone for your help. I found the problem.
First, I checked the power supply. Voltages are correct.
I checked the capacitance on all of the large capacitors. Capacitance was correct.
I replaced a couple of voltage regulators on the amplifier board. No change.
Problem Found! Under the keyboard, on the left side there is a small box with several input/output connections for MIDI, USB, microphones, headphones. There is a short circuit in this box. Some of the connections/ribbons from this box connect to the amplifier board and others connect to the CPU board. I disconnected the ribbon connecting to the CPU board and the keyboard worked perfectly. I unscrewed the input/output box from under the keyboard and allowed it to hang. I plugged the ribbon from the input/output box back into the CPU board. The keyboard continued to function properly....until I bumped the input/output box with my knee at which time the piano short circuited once again
Warning: Do not remove control/display panel back cover unless it is absolutely necessary. If you must remove the control/display panel back cover make sure you flip it completely up-side-down where the back panel is facing up. If the control panel back cover is not facing up when you remove it, all of the buttons will fall out. Putting all of the pieces back in correctly will require a couple of hours and patience.