It is with great shame that I come forward with this information.

I let a poor peruvianoid receive complete sun exposure to quickly after dormancy and the poor guy got a lil' scorched. I then left it in the rain for a month and now the tip looks like this.

What to do?

I'd say amputate it, or it will grow and kill your friend.

this

I figured as much.

Well I guess the root of the problem is over-watering from all this rain we've had. It's inside now so it wont get anymore water. I'd sort out the problem now but I dont have an adequate knife or sterilization materials.

Is sterile technique important?

The other 17" of the cactus are still firm and green, so I assume that means the roots are ok?

well I removed some of the outer waxy skin and then sliced out what was essentially a thin layer of brown mush.

It looks like the sunburn kind of blister'd and excess moisture got trapped between the outer skin and the flesh so I guess it wasn't rotting from within which is good.

I still feel like I dont have a clue whats going on though.... slicing and dice-wise.

sterile isn't that important, unless you are in a humid environment
if you are, dusting w/sulfur powder might be in order

let the freshly cut area scab over in a shadier place
and keep it dry until caloused

Awesome.

Always good to hear from dg on all matters spikey.

I've noticed where Ive made some cuts, parts of it are going brown, maybe darker in the same manner an apple would.

Is this normal, or do I need to cut deeper?

The initial discolouration was only the slightest more than skin deep.

I made this mistake as well. Who would've thought a freakin cactus would sunburn...but they do.

From my experience with cactus rot, its better to cut out a larger area then to lose the entire plant. I'd cut away all the brown goop and then another 10% just to be sure. Keep going until all you have is green flesh. Then just keep you fingers crossed.

This T.Mac got rot and it wouldn't go away. Lost about 18" of nice cactus.

^good advice
also, rotten sections extract just fine

as dg pointed out, the mescaline and other alkaloids dont break down during this stage of decomposition, the salts remain intact within the goo.

id slice it up with as little skin as possible and harvest the outter 5mm (goo included) dehydrate and powder. either extract or eat. dehydrated goo should be fine as there is no water for microbes to live in (however they might have made some potentially toxic byproducts so i would just extract the goo and eat the green flesh)

powdered cacti is best to extract ime, not teas

Ok here's two pics.

One when I slashed up two days ago and one taken this morning.

Should I just do a straight cut through the cactus below the dark bits?

i'd cut at an angle, which also prevents water from pooling

Yeah I noticed its pulled down in the middle.

Is it possible that all the sunburned areas may be compromised?

I made another cut, this time removing a little more and at an angle.

Let's see how it goes.

likely the sun burned areas will not cause further rot. keep things dry for a while, plant and soil

will just be an ugly spot near the base of your cactus in a couple years
dg