Fun stuff.
What did you do?
I used to dabble with custom ROMs years ago, so many aspects of ADB is familiar.
The nature of the problem was that I uninstalled Google play services using an adb command and then cleared the cache partition. From recovery it didn't let me sideload it back on and adb didn't let any shell commands because it was in sideload mode.
I was able to catch it in adb as a recovery device while it was stuck on the phone is starting screen and apparently the Google play services wasn't installed just hidden, so I had to make it visible and bam it worked
BH I had saved my computer as a trusted device just before I broke my phone.