Have a Dell 15 5551 from 2015. Had fast blinking alternating amber and white lights. Battery not charging. (Original power cord and battery.) Removed battery and ran fine off Ac adapter with solid white light. Used it, replaced battery back into machine( planned on getting new battery) and shut down. Now it wont power up. After power button long alternating amber and white lights but no start up screen....nothing. This is still plugged in to adapter so should operate on AC. I removed battery and working with no battery in it. Bad battery? Is there a proper process to reinsert battery I am unaware of?