One problem with re-programmed JLINK is that it still complains about lack of purchased license. The Black Magic Probe may be a good alternative...
I did the bluepill/stlink to blackmagic conversion, its not hard *once* you have the firmware, which for some reason no one uploads, all instructions have you compile it yourself.
Can load it with the built in stm32 serial bootloader or with a stlink.
It worked well until I did something to "kill" the chip (SAM D21). Of course, its atmel so they are fragile with the fuse settings, so its probably that. Currently I see no simple way to fix it with the blackmagic probe. The built in functions for D21 are limited (?), basically mass erase and read/write. It may be possible to run a program from memory that resets the fuses, I haven't tried that yet. Ended up ordering a jlink clone to see if that recovers it.