anne. 
I YOLOed this morning and turned on the 512k without cracking it.
It chimed!
...and then started billowing smoke after about 10mintes. 😂
The screen was still displaying all happily (I HATE I didn't get a pic of it), while the smoke was billowing so I'm thinking something blew in the power supply. As it goes. :)
This is the Macintosh 512K with the bad battery I posted a few days ago. Apparently, acid isn't an issue, only bad RIFAs.
Let's dig in. :) 
(1/5)
I was prepared to go 12 rounds with a iFixit kit getting the top screws loosened (I've been successful with this method on an Classic II previously), but it looks like they're already gone.
Could this be an upgraded 128K? (2/5)
Case cracked (I won't mention forgetting the screw behind the battery door 😅) and the interior greets us. At first glance, everything looks hunkey dory, but a closer glance finds the culprit of our billowing smoke.
I don't have a replacement right now, but this'll definitely be good for honing my soldering skills. :) (3/5)
I wanted to take a closer look at the board to make sure none of the battery acid reached the board. It looks pristine to my eye...but I took a (not)108MP shot of it if y'all wanna look at it really closely. :)
I also included evidence that this is indeed an upgraded 128K. Thanks to 65Scribe for giving a helpful guide to spot the changes in his Macintosh 512K video.
Are these rarer than an actual 512K? I dunno. (4/5)
The Macintosh 512K
And now reassembled.
This will be a fun future repair project. I still need to get a mouse, but I don't think that'll be too difficult to find. (5/5)
48kRAM@retronianne Ah cool - you only need the standard 512k analog / psu cap kit then. Yours doesn't have RIFAs at 33 and 37
@48kRAM Yeah! That's totally all I need...ahem....
(Thank you for knowing that and sharing...I was about to go on an absolutely clueless internet hunt. 😂)
@retronianne This should do ya
https://console5.com/store/macintosh-128k-512k-plus-analog-pcb-cap-kit-630-0102-661-0462.html/
Edit: You may also opt to do the logic board axials if you want:
Macintosh 128K 512K Plus Analog PCB Cap Kit: 630-0102 661-0462
<p>High temp, electrolytic cap kit for the Macintosh 128K, 512K, and Plus Analog PCB.</p> <p>Features correct specialized low-impedance and Nichicon axial caps, and replacement X1 or X2 safety cap for C38.</p> <p>Some, but not all boards use RIFA Y-clas
@48kRAM Hell yeah. :)
BrooklynMan (in exile) 🏳️🌈@retronianne you think they went to all of the trouble replacing the badge (or the case) too? or maybe they just lost the screws?