Thanks! I'm pretty sure I know how I blew it. I passed my resistance checks, failed a voltage check, tried to fix it be reflowing a couple of solder points and replacing a wire, and went straight back to voltage checks without doing resistance checks first (oops!) - turns out there were some resistances that I messed up.
It passes all the resistance checks again but I couldn't check voltage after the fuse blew. Hopefully all is well now.