my ipad won't charge - black screen or battery sign with red line only

These support pages should help with troubleshooting battery and charging issues:

Charge and monitor the iPad battery - Apple Support

If your iPad won't charge – Apple Support

Troubleshooting generally requires substitution of the Power Adapter and cable for another known-good item. Most models of iPad require a Power Adapter rated at 12W or greater to reliably charge. 5W Power Adapters intended for older models of iPhone are inadequate to charge an iPad; if the iPad charges at all, charging will be very slow.

Be aware that many computer USB ports cannot source sufficient power to charge an iPad. Unless explicitly designed for charging connected devices, computer USB ports are typically limited to 0.5-1A @5V (i.e., 2.5-5.0W).

If you continue to experience difficulties when using an appropriate Power Adapter of 12W or greater, you might be best advised to seek assistance directly from from Apple Support - and request a remote diagnostic test. You can contact the Support Team using the Support link at top-right or bottom-left of this page. Alternatively and perhaps easier, you can initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:

https://apps.apple.com/gb/app/apple-support/id1130498044

You might also visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your iPad, Power Adapter and cable(s):

Genius Bar Reservation and Apple Support Options - Apple

"my ipad won't charge - only a black screen with battery sign with red line : How do I resolve?"

-------

Troubleshooting iPad Charge:

A. Start Here: If your iPad won't Charge - Apple Support

B. Which Cables to Use: iPad Accessories - Power & Cables Power & Cables - Apple

C. Try what is on these Links:

• If your iPhone, iPad, or iPod touch won't Turn On or is Frozen - Apple Support
• If the Screen isn’t Working On your iPhone or iPad - Apple Support
• If your iPad won't Charge - Apple Support

D. Use an Apple Brand Cable:

Do not use a third party cable - cool though it may look, a fabric, third-part cable would likely tear - (Apple cable's are plastic and are intended for Apple).

E. About Battery Health:

Apple doesn't have Battery Health on an iPad. But, for note, Apple recommends that you get a new battery on an iPhone once its Battery Health reaches 80%.

F. A Faulty Device?:

So, is this covered under warranty? Note that this comes with a one-year, out-of-the-box, limited-warranty. So, set up a Genius Bar Appointment, asking them if this a faulty device.