Left blue joycon detected when slide in but showing white line on the

I can't get mine fixed. Fault happen when i updated and reset the switch but it's stucked on insert joycon as the left joycon(blue) can't be detected, changed the rails on the joycon and device. got it connected with the sound but its not showing blue line on the screen, it is showing white 🤦‍♂️. any suggestions? thanks