I'd use it but paying attention to how hot it feels: if it gets a bit hot then turn it off then disassemble and inspect it after it cools down

I'm personally very cautious about damage to/around batteries, due to !spicypillows@lemmy.world . At the very least, a photo might help depict the scale of the dent.

And while it might not be a spicy pillow right now, a damaged battery is more likely to turn spicy spontaneously. Replacement of the battery is, of course, the most risk-reducing move.

If it spontaneously combusts: problem

If it does not: no problem

Based on this iFixit link you should be fine.

Charge it and keep an eye on it to see if it swells. If it hasn't after a day, you're in the clear.

I would use it. Dents are just external damage, bulges are internal and much more dangerous.

Have you tried taking the back off and checking the battery? If its ok then remold the back plate to be flat and reassemble.

A tablet is mostly battery. If you can take it apart, do so and just bend it back in place.

Inside of most lithium batteries, it is basically a long set of ribbons that form a stack. They are wet like a clay and kinda oily (but still contained) on a ribbon like paper that is the width of the battery case/pocket. Then there are some layers of thin plastic that insulate the lithium ribbon.

It is not impossible that damage could occur to the center of a cell, but it is less likely unless the dent is sharp. The primary place that a cell gets damaged and where it causes problems is in the ends of the roll. If the end of the roll gets mashed, it is much more likely that layers can shorted out.

The thing to keep in mind is that something like a gasoline powered car uses a fuel mix of around 14 parts of air to 1 part of fuel. That means the atmosphere of Earth is providing a lot of your fuel requirements and it makes gasoline effectively like a super dense energy source. A lithium battery is proving all of the total energy in a single container. You don't get to remove oxygen from the equation if things go south. You need a way to contain the situation if things go wrong.

Over discharging reduces the life and maybe some capacity, but the main issue is if it will charge at all. Most lithium batteries have a specification for charging them from fully discharged, but not all charge controllers implement the circuit block that is required. All lithium chargers (should) have a duel mode where it is current limited then voltage limited. The fully discharged state requires a very low current trickle charge until the cell hits a certain voltage before raising the current.

The main concern is localized thermal run away. If it starts getting unusually hot or expanding, you're likely in trouble.

I've built robots and cat toys with lithium batteries and things like battle bots have them too. If you're always supervising and have a container and a plan if things go wrong, you can be fine. What you can't do is charge overnight or leave it unsupervised at all.

Quantum Immortality says you would never perceive a problem, because in the universes that it explodes, you die, and therefore unable to perceive it, therefore, you never split into that timeline.

🤓

it's non-zero risk of surprise fire, replace the battery and then you wont have to worry about it