Okay, so I had this problem with my Shark 6 months after I bought it. Tried everything... New brushes, cleaning, etc.. I finally got sick of this thing running for 1 min and stopping so I opened it up and took out the brush motor and gear. What I found was under the yellow square tip that physically spins the main brush roll was dog hair wrapped around the gear. The yellow square cap is actually removable and is just tightly pushed onto the motor gear (a small flathead around the edge should pry it off). I also noticed the bearings were very tight because when I tried to manually spin the gear, but thought it was normal. Ran the Shark after putting it all back together and it kept going for a couple days before it stopped again. I took off the main brush and was able to take the yellow square cap off without dismantling the entire Shark again and just dumped some oil right on top of the metal underneath (this is the gear bearing). I assume the dog hair/dust has dried out the bearing and making the gears hard to turn and motor overwork causing it to shutoff eventually.
Clean out the hair under the yellow square cap and dump some oil down there. It’s been running for a few weeks so far. Hope this helps.