I have obtained a couple of dead-battery Dyson vacuums in recent years. Aftermarket replacement batteries are available and so far, so good. The ones I installed offer somewhat increased capacity over the originals and performance is as good as I would expect. Of course aftermarket lithium ion battery packs are a crapshoot at best, so I stuck with ones that published at least plausible capacities and had a reasonable number of good/non-fake reviews. Given the price and lack of availability of OEM packs I'd say go for it.