I have some Merten CONNECT devices and they worked well, with exception of th 4gang battery 506004.
This device is not recognized correct from VERA. I tried at 1.x245 firmware. No success. Then I read that with 1.x.338 it should work. When I include it, I see only one appliance and error message cannot get any information on. I tried again to exclude the device. No chance.
When I contact the hotline, they have been so unfriendly and so snobbishly!! Normally nobody should buy any device from Merten. They are not intersting in solving the problem. The only answer: Buy the merten USB Tool (up 124 €) and start from the scratch.
When I told them that this is no option and no valid solution, there was the answer: we have no other solution and we are not willed to find one.
By the way: The device cannot be set to factory reset because this is locked. You need (nobody has it in his mind) the USB tool or you need to send it to Merten.
Summary: Absolutely unfriendly and incompetent. It is better to buy Fibrar switches.