12th week of flowering? do you mean 12 days? when did you flip the lights to 12/12? cause there should be buds! anyways what your describing me is root rot. your plant will definitely yield very very little or die if you dont address this issue. i would flush and clean your res. do 1/4 strength nutes with b1 or peroxide to address all that rotting. when roots rot it will lower the ph so it is key to keep an eye on your ph. this problem is from neglected abuse of not checking ph and possibly from the light leak. it could also be from the temperature of your water if it gets hot in your room