“lock failure disconnect and press reset”
Are these tethered or socketed units showing the problem?
I don't have experience with the Zappi, but on other chargepoints (socketed) that would suggest a failure of the lock mechanism: the socket has a pin that drops down to engage in a slot in the plug so that you can't unplug it while energised.
This can be caused by trying to engage the lock with the plug not properly in the socket, but can also occur if the locking mechanism is 'sticky' - lack of lubrication or out of alignment etc.
This is just guesswork rather than specific Zappi knowledge, but it might be worth isolating the power and taking the front off the unit to have a look at the lock mechanism. There's usually either a solenoid or a little motor driving the locking pin, and sometimes a microswitch to detect if it is actually in the locked position.