Your boss was on holiday that implies that the boss was out of the office for at least a day.
I am confused by your situation. You couldn’t start two of the forklifts, so you went to get help with that. It seems you couldn’t so what else did you do for the rest of the day?
As far as your boss asking you “to explain yourself” in front of others. Whether or not that is appropriate is situational.
I often have techs explain to a team of people how they resolved an outage or how they are going to set things up. That way I can get everyone up to speed on the effort or maybe other team members will identify things the lead had not thought of.
If someone was late for work, that would be a conversation I would have in private.