Laptop will not charge, blinking lights

So this is probably my fault for not using the Chromebook in months, but whenever I do try and charge it to use, it will blink a reddish-orange light and refuse to turn on. I hold down the refresh button, power, escape key, any combination, and it turns either green then green-orange, or just blinks greenish-orange and back to the reddish-orange. Both results do not result in the laptop turning on.

The charging cords I use both work, as I use them for other devices, and there's no issues with the adapter or outlet that the cords are plugged into. I know that the machine is charging, it just doesn't seem to be keeping that charge. This started... a very long while ago, it's just now that I'm concerned.

I would provide pictures of the lights, but unfortunately my phone is broken beyond repair and I'm waiting on the trade-in.

I suspect there's something wrong with the battery, but I currently have no way of cracking it open and seeing what's wrong, if anything. From what I can see, everything works fine otherwise. This has been happening for a long while, and I'm at my wits end. Any ideas on what went wrong?