How To Guide - How to manually switch the active slot

Android phones can now have an A and a B partition system for the OS and we can use this fastboot command to check and see which slot is currently active

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

fastboot change slot It may not flash TWRP as there is no active slot not bootable) If it is a slotted device in Fastboot run the command: fastboot getvar

fastboot getvar currentslot The inactive slot contains an older bootloader whose anti-rollback version has not been incremented If the active slot is then flashed with a build that fails