0V is actually fine, but if they were in reverse polarity for any length of time then they'll really be damaged:
0V is not the end of the world. If you trickle charge it back to around 3V with something like roughly 1/20th C. If you charge this dead 18650 with something approaching 5A, as the OP has desribed, that's over 1C, in the least. Do this, and the plating doesn't go back on, evenly, and this increases the chances of damage to the internal dielectric. This can lead to leaks and internal shorts. The latter, of course, can lead to cells unexpected turning into a hot potato and venting hot gas and flames.
There's relatively little energy left when the cell gets down to 3.0V float. It's not worth getting any more out, then having to trickle it back in to recharge. Also, you might expect to reduce the life of the cell when you discharge much under 3.0V, even if you trickle charge.*
So yes, I agree. 0V is perfectly fine. As long as you watch Clive's entire video and don't fall asleep.** I'm sure he explains this.
*I would assume any lumps and bumps that form over time tend to get only worse. If it were possible to discharge to zero to dissolve lumps and bumps, then plate the material back on smoother than before, I think someone would be making batteries that can be reconditioned in that way. If you reduced the amount of electrode material to the point where you could dissolve all the lumps by deeply discharging, I think the bare areas would not plate back. Hence, one way trip towards shitzville. If you discharge beyond 3V, the amount of electrode material that migrates is very great for little return. And Humpty doesn't go back together again as good as he started. Avoiding reverse polarity is a good idea. But we stop at 3.0V for efficiency and for #charge cycles of safe operation before leaking, lower capacity, and risk of internal short.
That's ~3.0V float. Under heavy load, it might be closer to 2.5V, where you want to cut your losses. Off-the-shelf voltage detectors made specifically for this task seem to bottom out at 2.7V, but we don't necessarily need to follow industry guidelines when we have our own design, life expectancy, and safety goals; we can make our own beds and take our own chances.
The fact OP's cells are self-discharging so rapidly, that is obvious sign of internal damage. They're a baby step away from internal short and possible meltdown. Even if the internal resistance is still good enough to run the laptop, it would no longer be a good idea. At least from the perspective of the laptop manufacturer's liability.
**And what the chances OP reads this far without falling asleep? Easier to just tell him his cells are damaged.