The green light on the panel and battery charger started flashing when away on a trip this summer, before fading away to be barely visible. Everything seems to be working ok so a bit puzzled.
It’s just a duff neon. Same happened to mine on Bubble after 15 years. You can buy suitable replacements (e.g eBay) and they are easy to fit. Make sure you get a 240V one, though. On my 2003 B32 the hole in the switch panel was 10mm dia.