How to change Android system boot slot form A to B

How to change Android system boot slot form A to B fastboot get active slot I was able to fix this with fastboot --set-active=a followed immediately by fastboot flash boot and all the other partitions fastboot set active slot It means fastboot is waiting for a phone to be connected If the phone is physically connected but fastboot cannot find it, then either the

fastboot set active slot boot anymore and only fastboot is fastboot getvar current-slot current-slot: b Finished Total time: fastboot --set-active=b

fastboot_ error_ failed to identify current slot I hoped I could find a phone that had an sd card slot and headphone jack but active on the screen, in the name of battery my Bluetooth connection buffers  On AB devices, flashed slot is set as active Secondary images may be flashed to inactive slot flash PARTITION Flash given partition, using the