Garage door won't open unless I hold the wall button down

My Genie garage door closes fine on all occasions but it won’t open unless I hold the wall button down. This causes real hassle as I can’t use my remote opener to open the door as well.

Here is what happening…

When it is fully open or close, left sensor – solid red, right sensor – solid green. If I block the sensors, left sensor blinks red, right sensor stays solid green.

If it is close and I press the wall button and let go, door would open an inch or so and stop. No flash on motor unit light bulb.

If the door is closing and I block the sensors, door stop immediately (does not bounce back up).

What could be the problem/s and how to fix? Thanks in advance.