Try pulling the brake arms apart again with your hand. That's the extra pressure the spring in the brake arm needs to apply.
When you disassembled the brake, did you remove the arm from the frame? There are 3 little footer holes for the spring to hook into. It may be that you need to get the spring into one of the "harder" holes.
Both brake arms should require about the same pressure to move by hand (ie with the cable relaxed and not doing any work) and the arms should not have any stickiness or unevenness in the range of travel.
Separately, can you easily pull the brake inner cable inside the outer? The V brake springs have to overcome all the outer cable's resistance plus the spring in your brake lever.
Its also possible to upset brake cables if your bike is in a workstand and the clamp is mashing the wires somewhere.
Once the brakes are "pretty close" you can fine-tune the spring tension using a hex or philips screwdriver into the nut that is underneath the frame mount. It will be really small. Tighten to make the spring firmer and have more pull-off pressure, and loosen for less pressure.
Also check that your brake pads/blocks are not hanging up on the tyre or rim anywhere. They don't move in a straight line and can contact the tyre as the blocks wear down. Also ensure your wheel's axle is fully seated in the frame.