Hi everyone, I really need some advice from experienced avocado growers. I grew this avocado tree from a seed, so it means a lot to me, and right now it's in critical condition.

A few months ago, we upgraded it to a larger pot, but it probably didn't have enough drainage holes, causing water to sit at the bottom. About one to two months ago, the leaves started withering and turning black one by one, so we pruned them off. Seeing no signs of improvement, we finally unpotted it last week to inspect and clean out the root system.

​Here is what happened about a week ago:

​The Repotting: I dug out the roots, washed all the old soil off with water, removed a bunch of earthworms（see Pic 4-7), and moved it into a new pot with fresh soil (see Pic 3).

​Root Trimming: I tried to trim some damaged roots, but the roots closer to the main base looked darker, while the outer fine roots were lighter and seemed healthier. I wasn't entirely sure where to cut without hurting it.

​Current Symptoms: It's been a week now. The top tip of the stem has started turning black (dieback), and the whole plant looks very stressed.I suspect it's suffering from severe transplant shock, root rot, or poor oxygenation, but I don't dare dig it up again.

​Should I prune the black dying tip right now, or leave it alone?

​How should I manage watering while the roots are recovering?

​Is there any way to save it at this stage?

Can I take a cutting from one of the branches to propagate and root it as a backup plan?

​Any advice on what to do (or what NOT to do) would be deeply appreciated! Thank you so much!

Need help with my avocado tree.