newbie sparkies first day wiring a subpanel with Klein tools gone hilariously wrong

so im on my first real solo job today installing a 200amp subpanel with Klein insulated pliers and screwdrivers, thinking im hot shit after watching that Electrician U video on subpanel wiring. customer calls me back in a panic because i accidentally crossed a neutral and ground, blew a $450 square d breaker and now the whole garage smells like burnt toast. gonna charge em $300 to fix my screwup but tbh i feel like a total clown. had to laugh it off with the homeowner or id die of embarrassment.