I would think if she still gets nothing after doing what you suggest Geohorn, that this would indicate the main fuse as more likely a possible problem, not the battery.
Another idea, take one battery terminal off and connect your jumpers to the other battery terminal and to the wire you removed. See if the lights come on then. If so, your battery is likely the problem.
It COULD or. MIGHT be the fuse... or it could be the ignition switch, or a broken wire, or a bad/corroded terminal or.... the list goes on...
I”m reminded of the time I was driving a “spare“ car I would leave at the airport because it was old but reliable. One day it wouldn’t start (no turn-over)....acted like the battery was dead. We jumped the battery from another running-car.... still no start... (it was daytime and the lights were not tried....but the horn would blow...convincing me that the battery was not the problem.)
This led us (all 3 of us were “mechanics” who should be able to diagnose such a simple problem) to decide it was a bad starter or solenoid. That Buick Skylark was low to the ground and parked in high-grass so we decided to rent a car and address it another day. Drove the 100 mile round trip, bringing back a new starter... still no start. Replaced the battery cables entirely...still no start. Each time another fully-charged battery was jumpered to the car for the start attempts.
Some passer-by-yay-hoo told us we had a bad battery, and of course we 3 “mechanics” (we all worked on aircraft in our day jobs) thought we had an idiot on our hands. I finally broke down and paid AAA to come get the car and tow it in (30 miles) and told them to call me when it was figured out, I had to get back to my day-job.
AAA called that next day saying it was fixed. All they did was install a new battery.
The OLD battery had two shorted cells that would pass current thru from the jumper-battery...but drew so much current itself that there was insufficient capacity to turn that engine over.
I had never before experienced a situation where a shorted-battery would short-circuit a jumping-battery.... but it darn sure did.
Not exactly THIS threads situation, but I’m provoked to consider that this may not be as simple as a blown fuse.... because if it IS a blown fuse....then bigger problems exist than that fuse! It blew for a reason.... that is likely still existing.
Just sayin’...