that mid piece in the trunk looks rotten. If you don't cut it off, you will likely lose the whole plant. not today, not tomorrow, but it is doomed. Don't know where you live, it makes a diff. I live in z9a so I cut my rotted section, knowing that I have plenty warm days ahead for the top to root and the bottom to develop shoots. here are some pics

Pics

whats left in pot

the top had an inflo (sniff). It is resting in a cool spot, callousing over. I expect for it to take root in 6-8 weeks.

It only turned dead like that from being in contact with the hot sand slash gravel. if I kept it on grass it would not have happen I live in new York. I'll make sure to cut and let start all over again. I got this from maui on vacation.

A really bad case on sunburn. Most likely on the soft green new growth of your plant. Bossy is right. The good news is since its putting out new growth it has a good root structure so it will recover.

If you're feeling really brave, you could cut out the middle and graft the top onto the healthy section of the bottom. Search this forum for info on grafting - and there's also a lot of info (including YouTube videos) online.

You know what I'm finding? I'm not loving graft wounds, no matter how neat they are. Since I trim branches to promote fuller canopies, I root the branches and if they're pretty enough, I make them my main plant and get rid of grafted plant. Just me.

anyway, my tip was sufficiently calloused so I dipped in rooting powder and stuck in the pot

Looks good.

great to see it coming back. It may be susceptible to insects which have had all season to multiply and mature so keep an eye out for signs of spider mites, etc. and give the tip an occasional cleaning with a garden hose.