Had an issue with my Crazy Kong board - the issue was me!
I bought a High Score Saves/Freeplay Kit, but it required me to remove the z80. No problem, mine was soldered it, but I can do it! I’ve removed lots of chips. I was careful with using my Hakko to not burn or lift any traces on the bottom. Got it desoldered, looked clean from the bottom, so I gently popped up the chip....
... and lifted some traces on the top.
Not to worry, not my first rodeo. I have super thin Kynar wire and fixed everything. Then I soldered in the socket, plugged in the kit...
Scrambled boot. Fsck.
I tried other z80s. Same thing. I used my logic probe. It was getting a signal and working, so it had to be trace related. I held it up to my worklight and looked very carefully...
A pin on the socket never made it in the hole!
I popped out that pin and soldered in a new one. Plugged it in and....
Boom! We good! HSS kit is in and working!
Nothing is more satisfying than fixing a dead PCB (especially when you killed it!).