I'm sitting here thinking "I've been here before".
About 20 years ago, in the "sandbox", I was monitoring special instrumentation on a calibrated engine. It was loaded with preservative fluid in the fuel system, and the test bench crew attempted a normal start without flushing the system first.
Ign on, starter engaged, fuel on at 10-15%. No light because of no Jet-A yet in the burner; but the preservative soaked the whole turbine section. Finally she lit - with lots of fire out the tailpipe!
The throttle jockey chopped the fuel AND disengaged the starter. BIG mistake #1.
Fire still burning, so he re-engaged the starter. BIG mistake #2. When the starter caught up to core speed, the impact sheared the quill shaft. Now we're unable to blow the engine dry.
Fortunately no real damage. And they drew a new quill shaft from stores, had a GOOD briefing, and repeated the exercise. Correctly this time!