The first thing you need to do is decontaminate the logic board with 91% isopropyl alcohol or else your phones lifespan will be decreased. Then you should try replacing the taptic engine. If replacing the Taptic Engine doesn’t work it’s a board level repair.
The battery was probably replaced. If you want to see your battery health download coconut battery on max and plug your phone in. It will give you all of the info on the battery like cycles and that type of stuff.