Did you manage to get the device working again, how do these parameters look on your device when you use 'fastboot getvar all'?
Code:
fastboot getvar all
...
(bootloader) has-slot:modem:yes
(bootloader) has-slot:system:no
(bootloader) current-slot:b
(bootloader) has-slot:boot:yes
(bootloader) slot-retry-count:b:6
(bootloader) slot-unbootable:b:no
(bootloader) slot-successful:b:yes
(bootloader) slot-retry-count:a:6
(bootloader) slot-unbootable:a:no
(bootloader) slot-successful:a:yes
(bootloader) slot-count:2
(bootloader) secure:no
(bootloader) product:bengal
...