Hi,

I haven’t tried it myself but it if you put the chip into DFU mode you should be able to burn almost anything (including burning the nordic bootloader I’m pretty sure). Burning a new bootloader without a J-Link is kind of dangerous, however, since if it fails you can’t recover.

In DFU mode you should be able to burn your elf file (or hex file). Particle does have a command line uploader (based on nrfutil as I recall) that should work.

Getting the bootloader to actually run the application may be harder because of the Particle security layer. If you can connect to the Xenon via the Particle mobile app that’s a better way to upload the program.

At the moment I can’t add much more.

I’d strongly recommend you get a J-Link. There’s a subset of a J-Link on the Nordic PCA10056 development board that might be able to upload a bootloader, if you can get that instead of a J-Link. There are also clone J-Link edu’s on Amazon for $10 that I have zero experience with.

Mark