Reser TRV Tuya TS0601_thermostat_4

[Snake40]

Good afternoon.
I am currently switching my home automation system from Domoticz + zigbeefordomoticz + Sonoff plus E USB Dongle to Home assistant + zigbee2mqtt + SLZB-06 ethernet coordinator (the 2 applications are in Docker containers on a Synology NAS). I do this gradually because some transfers are not obvious.
I recently integrated my Tuya TRVs identified "TS0601_thermostat_4" into zigbee2mqtt (https://www.zigbee2mqtt.io/devices/TS0601_thermostat_4.html#tuya-ts0601_thermostat_4) without difficulty. Following a total power outage, I lost the connection between the TRV and zigbee2mqtt. Until then... nothing but very banal... Where things get complicated is that the TRVs had the "child lock" parameter locked, in doing so, the zigbee re-pairing via the touch face of the TRV was proves impossible.
For the big problems, the big remedies, it remained to reset the TRV via its S2 microbutton as recommended in the documentation... Except that this also turns out to be impossible, as if locking the TRV by "child lock" also locked the actions on S2... Has anyone been in this situation before and gotten out of it or does anyone know of a "special" reset procedure that would get me out of the impasse I'm in?
I searched the web but found nothing. I sent a message to "my Chinese friends" but they remain silent for now...
Thanks in advance for any suggestions.