Surface 3 Pro Not Booting

3 year old Sfc. No prob until this past week. Now, when powering up, will show Surface logo screen, then MS rotating icon appears for about 3 sec then Sfc goes dead. No error messages, no powering down message, just goes black screen. During boot, keyboard does light up. Charger shows solid white light when plugged in. Can get into UEFI no problems. Hard reset no effect.
Any suggestions?