battery problem on 2016 Retina Macbook

Hi,

I wanted to get some advice before I take any action.

I have a 2016 Retina Macbook 12, that I just recently bought second hand. Mentioning that because I don't know the history of the computer. What I can say is the laptop has had no problems whatsoever since I've had it, until last night.

My Macbook drained to about 17% - after a good day of usage. Nothing out of the ordinary. I went to go plug it in for the night, and went to bed. In the morning when I unplugged it and tried to use it, the computer didn't start. I figured it died (thus maybe i didn't connect it correctly?) so I went to go plug it in again. It booted, and gave me a triangle with an exclamation point, saying I need to replace battery immediately (that is, this happened at the login screen).

I'm a bit concerned because the laptop is still new - Early 2016 model with only 54 battery cycles! I figured since it got very cold last night, I would just wait for the temperature to rise, but to no avail. I've already tied SMC reset but the battery still is claiming it needs to replaced. Not holding any charge - at 0% - and the computer is running completely off AC power.

The laptop was charging at an outlet with a fridge connected next to it, so I moved to entire new building (library) but nothing changed. Is it possible my battery literally crapped out over night? I was browsing around and downloaded coconut battery, it says the computer only has 45% of design capacity left. The battery is still registering with the computer to that extent. However, I was trying the SMC reset several times and the battery didn't even show up in the service report once. That just happened once, and when I reset it, it came back but still dead.

Checked the serial and of course, applecare expired a few months ago. Any further tips would help. Thanks!