I picked up this dying Macintosh IIci a couple of weeks ago, and have slowly been trying to bring it back to life. Here's what I started with: the PRAM battery was left in and exploded at some point, obliterating the case and corroding the clock chip, ROMs, and other components in the vicinity. Worse, it looks like this computer was set up on its side with the battery on top, so the released juices dripped down the side of the logic board and ate away at all of the ROMs and SIMM slots. All of that in addition to the usual level of capacitor leakage and ensuing corrosion all over the board. I'm not done yet, but it's been a fun project…
I managed to clean the board and get most of the faulty components replaced, except for the new SIMM slots. The battery acid severely weakened the top layer of solder mask, and a few chunks fell off as I was cleaning, so you can see some exposed copper in the upper right corner. This is a good checkpoint, because even without any RAM, the system should be able to boot and run the first part of the self-test in ROM. I powered up the board and got…nothing, because the ROMs that are soldered on the board are probably still damaged from the battery acid exposure. Thankfully the logic board also has a "ROM SIMM" to allow for replacement ROMs to be installed, like other Macintosh II series, and I had a spare SE/30 ROM SIMM that I could test with. The SE/30 is older than the IIci, so it probably isn't compatible enough to actually boot all the way to a working system, but it's close enough for the initial self test to run. And sure enough, with the borrowed ROM, I got the "sad mac" chimes, indicating that at least the CPU, sound, and ROM SIMM are still in working order.