Most of the problems with junipers tip browning has to do with fungal infections. It is pretty advanced. Get a sharp very clean pruner and cut off all of the brown tips, make sure you heat the pruner blade with a torch between cuts to avoid transferring spores. Lay some newspaper under the plant to catch the trimmings, you don't want to leave any infected material behind. Wash your hands and use disposable gloves so you won't transmit problems through touching infected material. Heat the blade of the pruner again and cut back the branches one at a time reheating the pruner between cuts til you come to healthy wood. Discard the trimmings. Try not to water the branches for a few day so the ends can dry off. There won't be much left, but if the surgery works, new growth should come out clean.
When junipers are severely infected with fungal disease sometimes it is best to just pull them especially if you have a lot of them and want to prevent the disease from spreading.
Happy gardening in Hawaii. Gardens are where people grow.