To convert his fitting then you would remove electronic ballast and wire the ends in series
Either way lamp is fitted there’s no short circuit
Is the starter actually a fuse or a solid link
If it’s a fuse it’s going to be required which means you can’t safely convert it there
Ya he has T8 and electronic ballast by the look of it so not compatible as is
Now that you mention it I think there was a few setups with these gadgets
What you bought is probably for magnetic ballast and starter type fitting
I think new starter and one end of new lamp are solid links to provide 230v at one end to power new led lamp
Think the electronic ballast type fitting you probably have needs the internals ripping out to manually supply...
You have to match and setup correctly and from memory there’s differences in them
They are another electrical gadgetry that manufacturers keep pumping out
Best option is usually new led fitting
Doh ya I forgot mine was shower only
Needs to be automated anyway not manual control, manual switches can be left off
I think I’d be leaning towards PIR suggestion