After a lot of investigation and internet searching, I came across this YouTube video, which was very helpful in understanding what was inside.
This did not solve the issue, but it helped me understand what to look for. In the video, he mentions you need a T10 security torx screwdriver. It actually requires a T10 torx (normal) screwdriver before removing the shell of the controller.
To solve the issue, I ended up buying a new controller keypad on Ebay for $33.90. MAKE SURE TO UNPLUG THE WIRES IN THE BACK OF THE WHEELCHAIR BEFORE REPLACING.
Pride part # RECPART1061
Merits part # P75736
Shoprider part # P75736
Keypad for 6 Key Button VSI Joystick Controller Pride, Merits,
As you can see, the on/off switch was worn down to the nub! See top switch/button in the first image.
If you need to buy a new controller, purchase a used one with the following name, not the part number shown in the question, as suggested by my durable medical provider. Pride (manufacturer) will not let you ask questions unless you have an account with them, so you have to trust the staff at a distributer, who in my case were wrong, and would have charged me for the copay of a $1750 controller, which was the wrong part number. The serial number of the chair did not give them the correct part number, so never trust that. Always look at the number on the actual component!
Correct part name:
6 Key 50 Amp VSI Joystick Controller with Flying Leads
Here's some detail if the keypad is bad, and you need to replace the entire controller.
Pride Mobility: CTLDC1419
PG Drives Technology: D50693.01
Compatible Models :
Jazzy 1103 Ultra
Jazzy 1143 Ultra