If you sprayed pesticide on the emerging leaves that is most likely the culprit. Sago leaves are tough as nails,except when they are still soft/new. It is possible it is the fertilizer as this can happen but I have bombed mine with super high doses of grass fert(high N, 21-1-3) and never observed this,not to rule it out but I would say less likely. So-this flush will be a dud,keep an eye on the plant(Caudex)though,just to be sure there isn't some hidden cause below.

My advice is to leave the plant inside, don't water it often and don't fertilize at all until you can situate your plant in a better spot. The goal is to starve the plant just enough so that it does not accumulate enough starch to promote a new set of leaves. They can easily be overwintered indoors this way. The same principles should keep the plant stable until you can give it sun. In the event that it does flush new leaves, just let them grow...they will be etiolated but you can cut them off next summer and let new ones grow. By the way, they do not by any means require heat in the 90's. Mine are almost through flushing a new set of leaves and thus far this year in the NE USA we have only seen predominantly below normal temps, rarely above 80. What you need is a well drained soil, high nitrogen but otherwise well balanced fertilizer, sun and some warmth, and regular watering during the warm months. Leave your plant alone. It will be fine when you give it a better home. Cycads have survived 200 million years - it was no accident. X

If the frond is on the lower end of the trunk it is natural for them to turn yellow then eventually brown. This is how the plant conserves energy for making new fronds. If the yellowing is occuring toward the apical end where new growth appears you are probably have a lack of nutrients. Sagos are pretty heavy feeders and actually like quite a bit of nitrogen in their fertilizers. There is quit a few good sites that pop up on a google search that give detailed care and feeding instructions. If you are in zone 8 a sago should survive outdoors most of the year. It would probably be happier outdoors. I bring mine in once temps drop near freezing. Good luck!

This looks like some sort of mechanical damage. I have no clue on what it might be, but the damage doesn't look like a disease of any kind.