No power, no charging light after battery fully drained

I have a Thinkpad T420 that I have installed a Windows 10/Pop!_OS dual boot on. I've noticed that the battery drains about 1-2% per hour when it is in sleep. I was away for a weekend and left it in sleep, the battery completely drained and now it has no signs of life at all. When I connect the charger, there is no status led and the charger draws 0.3w (I'm assuming the battery isn't charging at that amount of power draw. I measured it with a Kill-a-watt style meter.) The laptop does make a faint coil whine-ish sound when plugged in, but that's it. I have already tried leaving it on the charger overnight, as well as a reset by unplugging the charger, removing the battery and CMOS cell, and holding the power button for 1 minute.

Any and all help will be greatly appreciated. Thank you!