Return ConnectCore6UL to factory state

I am developing factory-programming for products containing ConnectCore6UL 256-256-W-BT modules. The devices I have contain custom (product) firmware.

I would like to return the devices to the “factory” state, as shipped from Digi.
I do not have JTAG available - only SD and UART.
I’m hoping that perhaps there’s a pre-built SD card image that I can download and use to reset the internal flash to stock state - which I assume wuuld be that just u-Boot is loaded on to the module?

You should be able to do it by following the instructions on programming the firmware.

No, this is almost the opposite of what I want to acheive – I want to get back to the no-Linux and orginal U-Boot-only statue.