Dyson have completely disowned this model and many others. No spares, or very limited availability, so service, no support.
Try and find a local vacuum guy. I need one as well.
my guess bad belts inside or worse.
it needs service , some have clutches that go bad.
i see no free service manuals on it, so ask them?
clean the whole vacuum , end to end, first. inside.
then check for bad or worn sticking parts to the drive head.
or just find a shop to fix it. (any can)
Dyson will supply parts but don't provide manuals to their appliances (in the UK) but provide a fixed price repair service at a price they consider reasonable (I don't).
Dyson vacs are designed to manufacture as cheaply as possible, they aren't designed for easy repair or replacement of components. I haven't much experience of Dyson but the little I do have has taught me patience and a devious mind are prime requisites to dismantle...
First check it is fully charged. Secondly, Try checking all the pipes, tubes and attachments for blockages. Basically take it to bits and clean it. Dyson have a 'cut out' feature fitted to stop you burning out the motor when it's blocked up.
The brush is activated by the suction of the vacuum. If it stops spinning, that means that either there is a broken part inside housing that surrounds the brush, thereby lessening the power of the suction to spin the brush, OR there is a lot of debris, usually hair, trapped and tangled around the brush. That can cause a troubling amount of friction and cause it to stop spinning. Either way, you will need an Allen wrench set to open up the trigger head. I found this video on youtube which details how to do that. It's not my video, but it is helpful. https://www.youtube.com/watch?v=FwNDO3pUxzM
Odds are it's overheating and can't breathe. Check for clogs in the wands (they are very thin in diameter). They can also clog in the lower hose and/or the long hose you use for attachments. If all that is clear your filter could be clogged. But it definitely sounds like it's overheating.