Even if u force s3 with kernel ur hardware on uefi level will not handle it properly and change that it will not go deep sleep or stay somewhere in middle of getting sleep with big chance u will get just black screen and u will have to reboot in the end. I am sorry s3 is really dead

B43 is reverse engineered driver for Broadcom it works bad actually quite often drops of speed for the net, so uninstall it and try apt install broadcom-sta-dkms this package