If its anything like other Turbomeca engines, the light will indicate that 30 sec power has been used - not necessarily that 30 sec power has been used for 30 seconds! It would be so much less confusing to call it OEI HI or the like, rather than "30 second power". Anyway, with that light on I would expect you to be able to start, though it might be inadvisable without first having a technician check the engine.
On the Makila 1A2 there is a magnetic reset on the engine. On the 2A it is via a soft key in the cockpit. With the Arriel, due to the age of the original engine, probably the former (reset on the engine) rather than the latter.