Burnt, should I throw it and start from zero?

Sad as it may seem, starting again is probably your most realistic option. If it was a photoperiod plant you could control the flowering cycle longer, so she could recover a bit and go on flowering, however, slowly. Being an auto, by the time she recovers to good health and strong growth, the flowering cycle could be well and truly over and will probably result in small flowers with compromised cannabinoid production/quality. Going to 12/12 for a 7-10 days before going back to 18/6 may not be as silly as it seems and may be one/the only way to rescue her, but without any guarantees. Being in a reduced light cycle will not stress her as much as having 18 hours and may allow for some repair to proceed before getting too involved with attempting to continue growing her flowers, which is a "high energy requiring" activity; something your plant is unable to do at this moment. A gentle 12 hour cycle may just allow for some/enough repair to occur during her night/dark cycle, which is why plants do need to "sleep" - to repair any damage that happened during the day and is something advocates of 24 hour light cycles don't understand. After 5 days of 12/12 you will know whether she is picking up or is a lost cause. You can only try. Sadly though, she may be beyond any help and starting again might be more expedient. Chalk it up to experience. Lots of maybes in this answer, but trying is the only way to find out accurately. They way you feel when you look at your plant is 10 times less than how SHE feels right now, so in reality, starting again is probably the only realistic option. The way she is now, will give you a little bit of poor quality flowers and if you are desperate, could be worth salvaging, but if you want to rationalize your electricity bill, planting new seeds is probably better. Hope you can make some sense out of my ramblings,..... and I hope this helps in some way,....... Organoman.