Thanks all for inputs. I have tried a few more prints since then and was able to get a almost perfect calibration print. Few things I did are
1. During build table calibration, I held back the building table with a two finger pressure on all four sides (also had a 500 grams weight in the center) and had a friend tighten the screws. This ensured that there is no warping.
2. The projected was a bit off (yaw). I had to use a level-checker to bring it back to the level.
3. I also noticed that the table on which I had set the machine on had an incline (the floor was not level as well). So, I mounted my machine on the wall