In performing the repair yourself using third-party components, you have forfeited all hardware and repair support from Apple. Similarly, any remaining device warranty is now void.
When replacing the screen of an iPad, the biometric sensors (FaceID or TouchID) are automatically disabled - and must be reset using special software that is only available to Apple Authorised Service Providers (AASPs). As such, loss of TouchID is an entirely expected product of your attempted/failed repair.
Even if you manage to restore basic button-operation by replacing the damaged flex cable, the TouchID sensor is now permanently disabled.
A remote diagnostic test by Apple Support, or an in-store test by Apple Technicians, will detect non-OEM parts - at which point service or repair by Apple will be declined. Your sensible option at this point, if full functionality is required, is to consider replacing your iPad.
Sorry, but insofar as Apple and hardware/technical support from them are concerned, you are very much on your own…