My iPad pro cannot charge due to the battery over discharged

Li-ion batteries, such as used in iPad, must never be allowed to remain in a fully discharged state - as they may never recover. If deep discharge occurs, the only remedy is battery replacement.

The tags appended to your post suggest that you have an iPad2. If you have an iPad2, assuming that the original battery is still installed, due to its age the battery will very likely have reached the end of its useful lifespan. As the iPad2 is obsolete, Apple no longer provide hardware support or battery replacement.

Even if the battery is could be changed by an independent repairer, the iPad will have lost all installed Apps and data; compatible Apps for obsolete iPad models have all been removed from the App Store - and therefore cannot be reinstalled.

For information, here is Apple’s advice for prolonging the lifespan of an iPad’s battery:

Batteries - Maximizing Performance - Apple

In summary, you should aim to keep the iPad’s Li-ion battery in the 50-80% charge range when infrequently used - or stored for long periods.