I made that mistake several times, but iirc it was always a recoverable error. When I stuck that hot loop into the agar it would sizzle, which would tell me I just murdered every bacterium that loop touched; so resterilize actually allow it to cool this time, and repeat the botched step in a slightly different location to pass through a section of bacteria that I hadn’t just dropped a nuke on.

…which is probably shitty technique, but it got me good enough results to get good enough data for class.