MacOS – way to bypass charge a 2019 MacBook Pro

This is by design. It's not helpful to fully charge a battery, and then use a little bit (say 2 or 3%) and then top it back up again. So purposefully, if you have fully charged your battery, it will not start to recharge it until such time as it has lost sufficient charge for a recharge to be worthwhile. It's all about charging your battery efficiently, resulting in minimal wear and tear where possible.

So, to try to illustrate it by example:

• You start with a flat battery, and charge it. It gets to 100%
• You move desks or something, resulting in a few minutes of battery usage, dropping it to 98%, then put it back on power
• The system decides it's not worth topping up 2% worth, and just sits there. The green light probably shows on the Magsafe to indicate that it's not even trying to charge, likewise the menubar icon shows a plug indicating full charge, rather than the lightning bolt charging indicator
• You use some more battery, say dropping it to 92%, before putting it back on charge. The system now decides that 8% is worth bothering about, and starts to charge.

Because you explain the problem perfectly, and in short:

• The battery does not charge, and your Macbook does only work with MagSafe attached

There's only one option what could be the problem...

The battery is dead, let me explain you why:

1. Your battery is ignored somehow, and your Macbook uses power directly from the MagSafe adapter. If you couldn't even use the Macbook with the cable in it, the cable could be the problem. Since it works with cable-attached, it's not.
2. You can use the macbook with cable in it as explained above.