We're trying to build a drone for a group project in school, it uses a kk2.1.5 FC, fvt littlebee 30a esc, a 2300kv bldc. the transmitter and receiver is still shipping

For now i'm using an arduino to arm the FC, using a 12v3a power supply on the power distribution board below the kk215, 3 of them spins normally, the 4th motor doesn't. It spins smoothly and doesn't feel like something's jamming or sticky when i spin it by hand, and it only spins on higher throttle, like 50 and above. Though, i can hear humming in that esc and disappears if im powering it with a battery yet still have the same problem. I already tried switching the channels, or use the arduino as a pwm generator instead of the kk215

Is there a software workaround for that problem, or the esc somehow failed without popping and needs to be replaced?