Click the power button until the green light turns on

Hold the blue tooth button until the blue light turns on

Open the setting of the credit card machine

Click on blue tooth 

Open blue tooth searching the available device
click on the device begins with SIM which the phone logo on the left side
waiting until paired

Printer will print a blue tooth pairing code if pairing correctly

Confirm does it match with the pairing code on the credit machine
kick the the box to allow accessing and then click the pair button (Reminder: the connection will stop if did not pair in couple seconds)

Congratulations! you are success to connect the credit card machine and printer