DLP 15.x agent install completes successfully however the  EDPA service will not stay running.

Error in the Agent Log:

Private key is not valid.
CoreServices.ComponentManager | Error starting components | [SYMRESULT 0x80010005] | ComponentManager.cpp(351)Communication.CurlTransportLayer | Private key is not valid. Error: error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt

The current private key included with installation package, does not match or was not signed by the certificate authority on Enforce.
On example scenario that would lead to this, would be if a package was developed and tested in a separate QA environment, and that same package was deployed to the production environment that operates off of a different Enforce server. Meaning the Endpoint certs were signed by the QA Enforce.

Also note that the EDPA service will be set to manual instead of automatic when this happens.

Uninstall Endpoint Agent software.
Create a new agent installation package.
Install with new agent package.

Assure that the account used to install has sufficient admin privileges such as local admin. 

Confirm EDPA service is created and set to Automatic startup.