Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, the only easy user doable checks would be on the ensuring that all the wiring and connections are done correctly and all pins present / not bent.
Still, the described symptom almost always point to an internal hardware issue or more particularly, possible suspects after a review of the Service Manual are:
If comfortably able and feel safe to do so, are you then considering a DIY (do-it-yourself) repair approach? If yes, do you have access to and familiar with a multi-meter and even a soldering iron?