Sat Nov 28, 2020 5:30 pm
The bootloader is used only at boot time, so none of the two will get used until you actually reboot the device.
Based on what have you concluded that the main bootloader is faulty? You could not boot the device except if you forced use of the backup bootloader by connecting power while holding the reset pushbutton? If so, setting force-backup-booter to yes is a safe choice; if not, I'd test that the backup bootloader really works before applying that setting, by forcing its use the above way.
A corrupt main bootloader should get fixed by a firmware upgrade (but this is also a conclusion from reading the manual, I've never needed that). So you may need a downgrade followed by a firmware "upgrade" (which I haven't tried, maybe it doesn't work) and then an upgrade back to the current version, again followed by firmware upgrade. If this doesn't work, only netinstall can help.