I wish I'd taken pictures.
I always check out the dog blanket box at Aunt Sallies etc: as I used felted woollen blankets as sound barriers/absorbers for music listening rooms.
$4- for the older Mountain Designs "Convertible"
Fill bath with warm water add 5ml of dish washing liquid and agitate by hand for 20 minutes or so, drain, rinse, add more water add disinfectant soak for half an hour.
Gently press out the excess water, spin dry for 7 minutes and put into domestic tumble dryer until dry to touch. Looked OK but still some dampness and lumps. Take to local laundromat and put into the big machine with a pair of old Crocs and put $2- in the slot.
10 minutes later and this bag looks like new.
So take note, even apparently dead sleeping bags can be revived, I would of course use a dedicated down soap for an expensive bag. But as this is for a 5YO Widget as a sleep-over bag at Grandmas house I reckon my money was very well spent