Make sure the TWS mode on both Tenos are entered by double tapping the bottom. The chime sound should come out from both Teno. You will hear the birds chirping sound when they are paired. Here are some suggestions to make it easier.
1) Try flipping both Teno upside down when performing the pairing. This is to ensure that there are no accidental touches from holding Teno or caused by the surface they are placed on.
2) Try using two fingers for the tapping the bottom of both Teno.
3) Please wait for up to 30 seconds for the connection as sometimes it takes a bit longer.
4) Disconnect the Teno from your phone/device's Bluetooth first and try the TWS pairing before connecting to the phone/device again.