Hyundai Smart Key gets locked once it is programmed or matched to a car. Keydiy KD-X2 remote maker can be used to unlock this key so that it can be used again with any other Hyundai i20 cars.
Example:
How to unlock/renew Hyundai i20 smart key?

i20 ID46 smart key 3-button

In keydiy KD-X2, select Chip Function->Automation detection clone->Start identifying

KD-X2 detects remote sensor is locked
Disassemble the smart key, take put key PCB and remove battery



In KD-X2, select Chip Function->Remote Renew->Hyundai KIA->V3 KeylessGo(PCF7953)

connect Keydiy kd-x2 and key PCB via remote data cable





Press UNLOCK to unlock key

Check again: Chip Function->Automation detection clone->Start identifying

Keydiy KD-X2 renew i20 smart key success.
How to Unlock Hyundai i20 ID46 Smart Key with Keydiy KD-X2