I think you will be needing a replacement battery. I found a battery replacement on eBay but i cannot guarantee that it will work.
[https://www.ebay.com/p/Replacement-Battery-C11p1611-for-ASUS-Zenfone-3-Max-Zc520tl-4030mah/6006451912|Replacement battery]
[https://www.ebay.com/p/Replacement-Battery-C11p1611-for-ASUS-Zenfone-3-Max-Zc520tl-4030mah/6006451912|Guide for replacing the battery] (Follow Step 1 thru 3 to replace the battery and follow them in reverse to re-assemble)