Ipad doesn't show its charging while off

pietradsm wrote:

it doesn't show it's charging while turned off

An iPad (or any other Apple product to my knowledge) doesn’t show anything when powered down.

even if I press the power button, no icon, nothing,

Correct. Starting the iPad from a powered down state by pressing the power button will simply show the Apple logo at first.

When shut-down, the iPad will continue charging per its charging settings, but will not have any on-screen indication of the iPad's charging or battery status. Similarly, iPad does not have an LED charging indicator. Be aware that, by design, connecting an iPad to external power while shut-down will automatically restart the iPad to its running state.

Information about iPad’s battery management can be found here:

About iPad and iPhone Charge Management Feature – Apple Support

While recent models of iPad offer the option to limit charging to less than fully charged, independent studies have demonstrated that restricting charging to less than 100% of maximum has little, if any, impact upon the overall longevity or health of the iPad's battery.

When set to 100% charge capacity, your iPad will optimally manage battery charging - and may automatically change its charging strategy by reducing the maximum battery charge level to about 80% of maximum capacity in certain circumstances, such as when being continuously charged in retail or kiosk applications. This strategy is intended to extend the life of the battery by reducing chemical ageing that occurs when the battery is continuously maintained 100% charge. When a “normal” charge/discharge pattern is resumed, charge to full capacity is restored.