Logitech k270 no power

Prakash Kumar you did not tell us if it worked before you replaced the batteries. IT could be that the batteries are installed wrong. It does happen so check on that. Double check the power switch make sure that it is working. Sometimes the batteries do not make good contact. See if they actually touch the contacts. If not, you can use some folded-over aluminium foil as extension. Anything after that would require you to teardown your keyboard. Something like this video might help

I have to purchase you keyboard so please contact me