Try this answer by Angel Genchev: USB turn write protection off
To turn off disk device`s write protect, we use the low level system
utility hdparm like this:
sudo hdparm -r0 /dev/sdb
where we asume that /dev/sdb is the Physical disk device we're working
on. If the device has partitions that are mounted as read-only, you
should re-mount 'em as read-write in order to write data to them.
Hope that helps.
You should run sudo hdparm -r0 /dev/sdb rather than sudo hdparm -r0 /dev/sdb1. So run your command but without the 1 at the end. You specify the device itself as a whole and not the partition number.