Have you tried "Cypress Programmer" instead of "PSoC Programmer"?
Using fw-loader appears to be the key.
Navigating to KitProg User Guide @ https://www.cypress.com/documentation/development-kitsboards/kitprog-user-guide
Kitprog User Guide points to fw-loader updates on GitHub.
I was using fw-loader from within ModusToolbox 2.1, which appears to be Version 18.104.22.1688.
I now installed fw-loader 22.214.171.1240.
I plugged in my bricked CY8CPROTO-062-4343W
Pressed SW3 to set LED2 to a slow blink
Navigate to the newly installed fw-loader/bin directory
Run fw-loader --update-kp3
within the text scrolling is the line:
Kit FW is 'KitProg3' ver. 1.01 b158. Upgrade file is 'KitProg3' ver. 1.21 b707.
This looks promising
PSoC Programmer now tells me I have the newer code - though it still gives me a warning.
I don't see the firware version when using Cypress Programmer. I'm guessing the version is showing up as a raw hex code. Understanding Cypress Programmer is a task for another day.
All seems good with CY8CPROTO-062-4343W now.
Yes, if you have installed the ModusToolbox, fw-loader, sure, will work.
And you found that great!
Meantime, if I remember correctly Cypress Programmer works better for PSoC 6 than the PSoC Programmer,
but anyway, it's not necessary anymore.
FYI, you can get Cypress Programmer from the URL below.