Hi student~!
Trying to lighten a unit is somewhat difficult....But I have set the unit on a styrofoam head and wet it and I have put it out in the sun and let the sun bleached the hair...it doesn't happen overnight but eventually it will be highlighted...you just have to monitor it and make sure no animals find it and take it away. I hope you have a back up unit so you can try this process...I have also used sun in blonde before with pretty good results outside which is quicker say maybe a couple of days...I know this sounds bizzare but I have done it and it will work...Once you have the color you want...then take it in and shampoo it and condition it very well. Youre other option would be to order an all blonde unit and try highlighting it with a darker color. Cheers