How to change the current active partition slot?

Fastboot firmware, ZIP firmware is official from Xiaomi EU ROM, TWRP and Card slot microSDXC Internal 64GB 4GB RAM, 64GB 6GB RAM

If you device randomly got stuck in fastboot after a reboot, that means the counter hit zero and the bootloader marked your slot as unbootable

fastboot set active slot stack trace: Error: failed to set active slot: Error: {error:{code:1,cmd:fastboot --set-active=b},stderr: waiting for any device >

fastboot change slot I managed to set slot A active with no further change and am now struggling to set slot B active fastboot --set-active:a fastboot