tried to pair two bluetooth modules. One module can be accessed in AT command mode. but another module is not getting access in AT command mode. That module is always in BT mode even during the POWERUP hold the switch it is not going in AT command mode
Being a bit more forthcoming on what Blueteeth you have and how they are wired might be helpful. As things are, the bet is that the second module you refer to is not what you think it is. It is possible to get an HM-10 on a board with a button that is not connected to anything, and doesn’t need to be.