EOL Hyundai Teva 20W 827 colour helical CFL that have ballast failure

I originally bought this lamp for researching purposes, because Semicom Lexis, during the CFL height, stated that this lamp have no liquid mercury and instead having an amalgam (Indeed Megamen CFLs started very dim because of this fact), and after seeing another variant at my first hostel starting at full brightness immediately despite the stating of amalgam.
This lamp also started immediately at full output.
Despite this lamp burned vertical base-down on my computer table lamp. and despite the vents at the top of the ballast case to keep the ballast components cool (And it indeed lasted more than 10 years I think), one time I wanted to turn on the lamp and it just did one flash, than went totally dark.
Strange that the ballast failed despite it worked at optimal conditions.