How to factory reset a locked phone when you cant access fastboot or usb debug mode
Some phone needs to be plugged to light before it can boot to recovery mode/hard reset. Try putting the plugged charger in the phone when it's switched off and immediately it shows the charging signal press the volume down⬇key+power key, if that doesn't work try volume up⬆key+power key.
The both work for my phone innjoo i2s.