LED comes on, fan comes on, but no chime.

This series uses An iGPU (Intel Iris 5100), as you are getting power so either the logic board has a failure or the CPU/iGPU has failed.

You’ll need to open the system up and make a detailed inspection of the logic board looking for damaged components. Follow this guide Mac mini Late 2014 Logic Board austauschen and review Steps 10 ~ 12 in this Mac mini (Ende 2014) Teardown to help you identify the major components. If you see something suspect take a tight picture as well as one to help identify when it is on the logic board posting it here so we can see it.