HP EliteBook Folio 1040 G1: Power and charging lights blinking

I have a HP EliteBook Folio 1040 G1 (i7-4650U, 8GB DDR3, 256GB SSD) which was working until last evening. Now, if I plug it in, I get a power button blinking on and off, and the charging port blinking between orange (amber) and blue (turquoise). I bought this laptop from a refurbisher, and it has a non-original battery.

I have opened the laptop, unplugged the battery and CMOS battery and plugged it back in, to no luck. I have also pressed the power button for a minute, and still get the issue. I am suspecting that the battery is dead. I have learned that unlike other laptops (Dell, Lenovo), HP routes the charging port power through the battery and then the motherboard, and a dead battery on a HP means a non-usable laptop.

It can also be a motherboard issue on the HP. Fortunately I have another (slightly newer) laptop (Dell Inspiron 2-in-1) which is use for mostly schoolwork and internship (where the HP is used for non-school/work stuff). Maybe the Dell will become my one and only laptop if the HP fails.

I have ordered a new battery (for the HP), but is this problem a battery one or motherboard failure. Or is this issue just that I need to leave the laptop for a few hours. Please help.