TGT882,
If I EVER catch you NOT reengaging the starter PROMTLY when you have and internal fire, ei the senario you just described, I will personally drink a lot of beer on your credit at your local pub. Well joke aside, what you describe in your post is a rare phenomenon, especially on small jet engines, but it can happen never the less. Itīs caused by an internal fire fuelled by engine oil and the only way out of it is to engage the starter and let it cranck the engine until the tgt or egt is lowered.
Brgds
DOC