Fault in Zigbee ZG-003-RF controller - series of impulses instead of one

I added a ZG-003-RF controller to the gate drive. Sold in bulk on Chinese electronics portals. It works via Zigbee with the Tuya network (but not only).
Worked perfectly for a year. Without any intervention / programming, instead of a 1s relay pulse the controller generates a sequence of pulses. This is illustrated in the video below. The actuation on it is via the local keypad, but control from the app has the same effect. The effect is analogous on the other channels.
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The other modes of the controller - permanent ON/OFF and "roller shutter control" work correctly. Zigbee re-pairing does not change anything. Only the "pulse" mode is faulty. But it is the only one suitable for controlling the "open", "close" and "gate" inputs.

Inside the housing, of the relevant components we have:

XL1509 - 40/5V inverter
ULN2003 - driver for relays
STC15W204S - 8051 microcontroller with FLASH, RAM, EEPROM
LDO3,3V stabiliser
ZT3L - Zigbee / Tuya module

I powered the controller from the 24VDC output of the gate - just like the photocells.

I replaced the controller with a new one, because when you get used to the convenience, you will spend 100PLN to have the gate open by itself from the car again.
But I am very puzzled by this fault. Because there is no indication of a typical failure, just some kind of software error.

Does anyone have any ideas what else to check or reset?

Added after 6 [hours] 25 [minutes]: .

I would also add that the "sequence" generated by the controller on its outputs is normally broadcast via Zigbee, gateway, Tuya ecosystem to the application. That is, even though I excite the output with a microswitch I get a series of "blinks" of the on-screen button in the application.

Very interesting problem, but I don't know if anything much can be done about it. I would try the following things:
- how did you pair again? when you removed the device from the app, was there only the "remove" option or was there also "remove and wipe data"?
- when you pair with a fresh Tuya account is there also this problem?
- how does this MCU work there, is it a TuyaMCU device and this Zigbee module is connected via UART to the MCU and the MCU directly handles the relays and buttons? If so, then the buttons work when the Zigbee module is soldered out, yes? And does this problem then also persist?
- I wonder if, as if I paired with the HA via Zigbee2MQTT, this problem would continue

p.kaczmarek2 wrote:

Very interesting problem, but I don't know if anything much can be done about it. I would try the following things:
- how did you pair again? when you removed the device from the app, was there only the "remove" option or was there also "remove and wipe data"?
- when you pair with a fresh Tuya account is there also this problem?
- how does this MCU work there, is it a TuyaMCU device and this Zigbee module is connected via UART to the MCU and the MCU directly handles the relays and buttons? If so, then the buttons work when the Zigbee module is soldered out, yes? And does this problem then also persist?
- I wonder if if, as if paired with HA via Zigbee2MQTT, this problem would continue

.

1) The Tuya app just "forgets" the device in the gateway. You have to force a new pairing from the controller's local keypad.
2) I can't test now because I only have one Tuya-Zigbee gateway and changing the account would "scatter" the rest of the configuration.
3) The "8051" microcontroller is between the Zigbe module (sprouted only 4 I/O pins and power, the rest NC) and the rest of the electronics (keys, relays, diodes, RF module).
4) I have a colleague from HA and I know he uses an analogous module. After the holidays I will visit him and try to pair in his ecosystem. For Tuya too, by the way, this is not some concurrent Zigbee module just a "generic 4ch button".