if the laptop is a 2012 or later, have a look at opencore legacy patcher (https://dortania.github.io/OpenCore-Install-Guide/)
I'm running Sonoma on a 2013 macbook air, 2x 2014 macbook airs, 2x 2015 macbook airs (all 11 inch, 4gb), a 2012 macbook pro (with the dvs, 16GB ram) and a 2015 macbook pro (i7 16GB ram).
I recently picked up a 15 inch 2015. Temperatures sit around 60°C (noting it is almost summer here), fans are around 2000rpm. They are not audible over the ambient noise in the room. When the fans do spin up to max they are noticable. They're comparable to the fans on the 2018 and 2019 pros.
1080p video playback (youtube) does not induce audible fan noise, nor does basic web browsing. Geekbench and cinebench do get the laptop cooking though (temperatures hover around 96°C)
Let me guess... this is a 13 inch 2018 macbook pro. If so, you're the proud owner of a macbook pro that has suffered what is being called (smh) "dustgate", in which pieces of dust and debris can get behind the plastic screen cover (that has the Macbook Pro label on it) in two places that happen to coincide exactly with the position of the two data flex cables. When the screen is open, this debris can happily sit on the cable, but when the lid is closed, the cable pulls tight against the cable guide and between the guide and cable, the debris is trapped. If you're unlucky, the debris can pierce the flex cable and break one of more of the data tracks within. In Apple's obsession with thinness, the cables do not plug into the screen, but rather are soldered onto the PCB within the screen. What's worse is that the PCB is actually behind the screen, so to replace the cable means to dismantle the screen - usually resulting in a destroyed LCD panel.
I too have suffered from this situation and for the interim, my 2018 has now become an under desk mounted clamshell desktop machine. I'm also rocking a 15 inch 2015 macbook pro (i7, 1TB SSD, 16GB ram) which I got myself as a replacement (don't tell my wife).
If it is only on the keycap (and has not gone into the keyboard mechanism), my recommendation would be to let it dry. You can always get a replacement keycap off amazon or ebay. A trip to the Apple store may even get you one for free - if they happen to have a dead macbook hanging around out the back.
If you don't have filevault enabled, you can change your password via the macOS recovery (via google: https://nordpass.com/blog/how-to-reset-mac-password/)
if you do have filevault enabled, you'll either need your password to decrypt it in recovery mode. Not that if the issue is with the macOS installation, your password may actually work to decrypt your drive in recovery mode. If so, you should be able to reset your password using the steps in the link above.
Best of luck
You've fried the backlight driver. IIRC this is on the motherboard and would require a replacement. A replacement can be purchased on ebay (I think ifixit may also sell them). Replacing the board in a 2015 macbook air is quite simple - you just need the correct tools - a pentalobe screw driver and a torx screw driver. These can be purchased from ebay or amazon for a few dollars.
I agree 100%, this what I was actually told from an authorized repairer when I needed a battery replacement (they were going to charge over $200 for it).
To clarify, I was told that if I took my laptop to a place that Apple hasn't authorized, they'll use dodgy parts and likely install malware. I'm not saying that a repair shop would actually do that.
your only option will be to take it to an (and this is an Apple term) "UNAUTHORIZED REPAIRER who could also install malware on your computer). they'll likely replace it with an aftermarket battery - simply because Apple doesn't sell them any more.
Your alternative is to watch youtube videos, read the ifixit battery replacement guides, and then do it yourself. The important thing to note is the retinas have glued in batteries - apparently screws make laptops thicker (even though the battery on the airs are screwed in 🤷♂️). 99% isopropyl alcohol will help greatly in disoling the glue.
You can get USB enclosures from Amazon. But if you want to simply wipe the disk, you could create a linux USB using your windows PC and then boot your mac with that. Ubuntu works well on the 2015 macbook airs. The live USB will allow you to repartition the SSD.
This is now officially being called "dustgate". It is caused when dust (or other particles) get into the screen via the plastic cover (with macbook pro). These particles can then settle on the ribbon cable, and when the lid is closed, the particles can push into the cable and cause the tracks to break.
There has been a recent uptick in reports (on reddit and other sites). I'll also note that I too have had it happen to my 2018 macbook pro just a few days ago.
Apple has acknowledged the problem (in that they fixed it in 2021) but have not yet offered a repair program for it.
I'm currently using my 2018 as a desktop machine, awaiting for the repair program.
2016 - 2020 are not worth anything these days. The 2016 and 2017 suffer from "flexgate" - in which the backlight cable is not long enough and eventually breaks - and they all suffer from "dustgate" - in which dust (or crumbs) can enter into the lower portion of the screen and break the tracks on the data ribbon cables, resulting in a pink screen to be displayed.
You're better off getting a 2015 macbook pro, or save up for an M series (in which Apple has fixed the dustgate design flaw - even though they've not yet admitted it to be a design flaw)
Prior to deleting AlDente, did you follow the uninstall procedure
https://apphousekitchen.com/how-to-uninstall-aldente-pro/
If not, I'd recommend reinstalling it, then do the above steps prior to uninstalling.