O Learned Denizens, only my second post to your hallowed halls so please go easy on me.

2010 XF with halogen H7 headlight bulbs. Right hand failed a few months ago and I changed it without incident, apart from cursing the person who signed off that delicate tab on the top, which was pre-fractured of course. So I am notionally capable of changing a bulb.

Left hand just failed, replaced the bulb, no joy. Reading in the manual I see there are no fuses but instead a Field Effect Transistor protection.

So now I am baffled what to do next. Any pointers?

I'm OK with a multimeter but I need to know physically where I am pointing the multimeter and what a happy multimeter looks like.

Ah-ha!

Got the multimeter out today and patiently pinged everything through. Upon doing so, I discovered that in turning the headlight over I had foxed myself and swapped out the high beam bulb instead of the low beam. I hadn't thrown the old bulb away - because I thought it looked like a good one - so I just reversed my error and swapped the real blown bulb. 

Crisis averted! And some kind of lesson in hubris; it will teach me not to claim I can change a bulb again. 😉

...at least you did only claim to be "notionally capable"!

As Eric Morecambe might have put it, The bulbs were all there, but not Necessarily in the right order!

🤣