1000 imp/kWh means that LED will flash 1000 times for 1 kWh.
There are 86,4000 seconds in a day. 2.6 million seconds in a month.
At a rate of 21s/blink, that means 123,429 blinks per month, or 123kWh. Which at 21.8sen/kWh works out to RM26.81.
At a rate of 40s/blink, that means 64,800 blinks per month, or 65kWh. At 21.8sen/kWh this would be RM14.17.
Not familiar with this model. On some meters, if you hold down the button for more than 3 seconds, it will display two decimal points after the kWh. On most homes, you should be able to see the numbers moving.
If your neighbour is stealing electricity, you should be able to see wires snaking from your house to theirs. They cannot steal electricity wirelessly.
If the LED is blinking every 40s, it will take 400s (just under 6 minutes) to reach 0.01kWh. Turn off everything. Check the meter. Waith 15 minutes. Check again. If it increased, then there is a problem with your meter. Get TNB to change it again, because this one is faulty.

I m staying in condo and using smart meter, can my neighbor stealing my electricity. I dint see any snaking wire from my house to their